Information On Imperial Oil Types and Additives


Imperial Home Page -> Repair -> Engine -> Oil Types and Additives


What is Viscosity?

"Viscosity is the measure of how thick an oil is. This is the most important property for an engine. An oil with too low a viscosity can shear and loose film strength at high temperatures. An oil with too high a viscosity may not pump to the proper parts at low temperatures and the film may tear at high rpm.

The weights given on oils are arbitrary numbers assigned by the S.A.E. (Society of Automotive Engineers). These numbers correspond to "real" viscosity, as measured by several accepted techniques. These measurements are taken at specific temperatures. Oils that fall into a certain range are designated 5, 10, 20, 30, 40, 50 by the S.A.E. The W means the oil meets specifications for viscosity at 0 F and is therefore suitable for Winter use...

...Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

Multi viscosity oils are one of the great improvements in oils, but they should be chosen wisely. Always use a multi grade with the narrowest span of viscosity that is appropriate for the temperatures you are going to encounter. In the winter base your decision on the lowest temperature you will encounter, in the summer, the highest temperature you expect. The polymers can shear and burn forming deposits that can cause ring sticking and other problems. 10W-40 and 5W-30 require a lot of polymers (synthetics excluded) to achieve that range. This has caused problems in diesel engines, but fewer polymers are better for all engines. The wide viscosity range oils, in general, are more prone to viscosity and thermal breakdown due to the high polymer content. It is the oil that lubricates, not the additives. Oils that can do their job with the fewest additives are the best. "

Detergent versus Non-Detergent:

"...DETERGENT/NONDETERGENT- Detergent additives are just surfactants which lower the surface tension and allow small particles to remain in suspension more easily. This is to transfer contaminates to the filter so they can be removed. You do not want deposits to form throughout the engine because that makes them hard to remove and insulates the passages so that the oil can't remove and equalize the heat. The base viscosity is increased somewhat by other additives to compensate for lower surface tension. Back when overhaul intervals were shorter, The deposits would get cleaned up periodically before they got too bad. I wouldn't use nondetergent in an engine with modern parts...."

 The article continues;

 "....One problem you can have as mentioned by others is adding detergent oil to an engine that has a huge amount of deposits in it. As the detergent softens these deposits, there is a risk of a chunk coming loose and blocking something. The risk is real but then if you have this much stuff in there, you have a time bomb waiting to go off anyway because a big temperature swing can trigger the same thing. The right answer is to tear it down and clean it up. My answer is to run detergent oil, at moderate load, and change oil and filter frequently for 3 or 4 changes and hope for the best...." 

If you read what's at this link you will find some support for keeping same/same, but it still really depends on the interior condition of the engine in question. Having now become an "OLD TIMER" in the car biz, I have run into this question a lot, and I think this page/link above does a fair job in explaining a lot of oil issues. The "state of the art" in oil and engine development went hand in hand, but engines built without oil filters, as many were, could not benefit from detergent oil. In fact keeping all that carbon in suspension actually did harm and shortened engine life. Most car makers whose engines used oil filters recommended detergent oil, except for an early few that used live rubber seals as the detergent softens/swells and causes premature seal failure. Once an engine has been rebuilt using current materials (in use since at least the mid 50's) detergent oil is only an issue if you have no filter.

Question from Tony:

Well tonight I started on the job of putting new valve stem seals in my '69 Coupe. I figured since the trnas is out already for the rebuild ,,,may as well do a few things to the motor. What I found was rather heart breaking. I was working on putting the seals in when I noticed a greyish-white milky subtance in the heads.. well I have not checked further tonight, but my first thoughts are either head gaskets,, or even worse..heads!!! This is not a very inspiring find since I know that it is an expensive and rather unpleasant experience.


From Pete:

If you're talking about a small amount of grayish-white pasty stuff that has accumulated in the head casting nooks and crannies I wouldn't worry. I've torn down many engines that had this condition. AFAIK it's just stuff that drops out of the oil or by-products of the oil's reaction with moisture from normal engine breathing.

If, OTOH, you have a thick coating of dirty white slime on the head and inside the valve cover, then you might have more serious problems. What does the oil that you drain from the engine look like?

From Paul:

If that white milky substance is serious, you will have also seen it on the dip stick when you pull it out to check your oil. This would usually mean that water is getting into the engine via blown head gasket, or cracked engine casting (block or head). Oil and water mix to make this mushy subtance.

Sometimes it appears simply from condensation from sitting. If it only appears in the valve covers, this may be the case.

From Demetrios:

Sometimes, by trying to fix imaginary problems, you may end up creating real ones. If the head gasket is not leaking coolant, it may be best not to remove the heads. There is some chance you do something wrong in the reassembly. If your valve covers are off, you may try to clean the return oil holes from the heads to the oil pan. This would be my thought...

Question from Ken:

What BRAND of oil does everyone prefer and/or recommend? I have a 1970 LeBaron 4 Dr. hardtop with an original, unmodified 440 that has 140,000 on the clock. I have seen all the oil commercials and heard all kinds of crazy recommendations; but I want to hear what IMPERIAL owners put in their crankcase.


From Roy:

I use Mobil 1 10W40, full synthetic along with a Mobil 1 micro filter. Both expensive, but with less than 2000 miles annually the oil only gets changed once or twice a year.

From Bob:

I prefer Havoline 10W30 in all my antique autos, and use Fram filters.

From John:

I use Castrol oil & Fram filter.

From Patrick:

I use 40 weight in my 413 with 79000 miles on it. It consumes some of it and the engine is ready for a rebuild I'm certain.

From Rich:

I use straight 30W in my '66, but 10W-40 in my '73. The '66 with 115,000 miles does use a quart between changes (every 2000 miles). My '73 doesn't use any oil between changes, and that car has 80,000 miles.

From Ken:

I use in summer, 3 quarts of 10/40 and 3 quarts of 10/50.Oil pressure stays high ,even in extreme heat, also engine is cooler. It does not get driven much in winter, how ever, I do make it all 10/40 during this time. The oil being used by your car, check for leaks, if there are none, new valve seals. The valve seals sound harder then they are, if you're mechanically inclined itís a snap.

From Mike:

I don't use synthetic, #1 because it costs a ton and #2 because I don't think the benefits for my 67 Imperial are that much more than using a good conventional oil. Synthetic oils leak more, so unless you have a newly redone engine with nice, tight seals, you will find more leakage. This may not be a major concern- heck, you may even appreciate the perpetual front chassis lube. But, your oil consumption will increase as a result. I have also HEARD (and take this with a grain of salt) that synthetic oils do not cling to metal parts as well as conventional oils, so cold starts can be more damaging, esp with engines with large clearances. The newer synthetics may not have this problem.

Bottom line: I would use synthetic in a new car or with a rebuilt engine. Maybe I would use it also if I drove my Imp like a bat out of h*ll every time I took it out. Otherwise, I'd stick with Dino oil. Personally, I use Catrol 10W-30, or 20W-50, depending on the engine and the conditions. I change oil once in the spring and once in the fall, regardless of miles, and I usually only have 3000 or 4000 miles MAX between changes on my old cars. My Imperial has only a tick over 51,000 miles, so 10W-30 goes in at the fall change, and 10W-30 in the spring change but I top off with 20W-50 during the summer and 10W-30 in the winter. I like Napa/Wix filters the best but the Purolator Pure1's are decent too, based on some testing I have read on them. I stay away from Fram.

I also have a Volvo 122 that I use 20W-50 in all the time, as it has 200,000+ miles and smokes a bit, and the oil pressure sometimes gets low.

From John:

I have had a long time experience with synthetic oils. Mobil 1 was the first brand of synthetic oils on the market back in the mid seventies. I have been using it ever since. In my opinion they still make the best product. When the oil first came out, there was a problem with the engine seals shrinking. I personally experienced large amounts of oil leakage in one of my mopar vehicles after extensive use. After a couple of years of perfecting their product, they fine tuned the formulation to fix the gasket leaking problems. I can't speak for other manufacturers. The way I look at it, not only does the synthetic oil cut down on wear, but it also saves me time and maintenance. I have always changed my conventional dino oil every 2 to 3 thousand miles. With the synthetic oil, I have extended that interval to what new car manufacturers recommend these days, 7500 miles. Since Mobil did at one time say that they recommended up to 25,000 miles between changes, I feel perfectly safe with the 7500 mile interval. (I did think 25,000 was a bit extreme). There is only one instance where I would not use a synthetic. The reason being is that it lubricates so well, that it could be a problem during a break in period. When I rebuilt my 440, I initially put synthetic oil in it. That was a a mistake. It kept smoking for a thousand miles. The rings would not burnish and break in properly due to the synthetics high wear protection. I drained the oil, put conventional oil in it and the smoking stopped within 50 miles. After 2000 miles with the conventional oil, the synthetic went back in and it has been happy since. It will go 7500 miles without adding a quart and is leak free. I also use synthetic in my Harley. It gets a heavier weight because the tolerances are looser and because it is air cooled. In fact I even use the same oil in the transmission. Have for the past 10 years without any problems. For a newer car like my wife's 2001, I use 5W-30 or 0W-30. It improves gas mileage and the closer tolerances are designed for this weight. If you look at the service ratings, synthetics have the highest API ratings. They always exceed the latest tests. All of the expensive high performance vehicle manufacturers recommend Mobil 1 exclusively (Viper, Corvette, Ferrari, ...).

From Ed:

I use Castrol 10w-30 in everything and also use NAPA Gold filters. I change the oil and filter every spring and fall on my older cars (they don't get that much mileage) and every 3000 mi. on my daily drivers.

Question from Dan:

I know that 30w oil is recommended by most for an older engine, and race engines use it too.

But, what is not so good about using multi- viscosity oil?

Isn't it supposed to change with the temperature? When the engine is cold, it is thinner so that it is easier to start and get it pumping. But, when it's hot, doesn't the viscosity go up, making it in effect 'thicker'? (Try starting your car at -10 degrees F and tell me 30w is better.)

Also, I have always thought that synthetic oils are supposed to be far superior to other oils, because it doesn't break down as fast, and it clings to the engine parts longer, providing better lubrication at initial startup. Or, is this a bunch of hype?


From George:

On the oil for older cars Question, I have never owned a newer car, and never will ( could not afford one if I wanted it anyway ) so I have driven a lot of miles in the likes of 58/59 Desoto's etc, and here in Australia where we do not have to worry about Freezing, I always have found a straight 50 Grade oil suites these old girls the best. I have even done my far share of Drag racing ( on a Drag Strip ) with 361,383,413 Motors so I sure have tried to stress them to the max, and it has been the straight 50 grade that has held them together. Now to take it one step further I am now a firm believer in some of the oil additives now available, I use slick 50, it is very expensive, but it does work. Three years ago I changed the oil in my 71 318V8 Valiant Wagon and added the Slick 50, since then I have NEVER changed the oil, and as it has a leak, I only buy the cheapest/nastiest oil form K-Mart etc, this stuff is so thin it is a wonder it does not evaporate in the Can! and let me tell you I give that old 318 a Hard time! it still runs quite and blows NO smoke, so I am a believer.

From Dave U.:

Change the oil fast!! As the car is driven oil additives break down due to heat, dirt and contamination from gas and moisture and keeps varnish and other deposits from building up. If not removed these deposits will clog up the oil passages and damage the bearings leading to engine failure. Filters take out the dirt, or most of it anyway but you still need to change the oil regularly!! Also don't just change the oil, you need to flush the engine out too. Slick 50 and the other additives reduce friction which reduces wear, that doesn't mean quit changing the oil. I just hope you haven't damaged the engine already, good luck!

From Dave:

I put in Slick50 the first oil change I did on the 67 2 years ago and almost immediately developed a knock. I changed oil again and went back to the Quaker State 10-40 that my father-in-law used for 30 years and noise went away. One of my workmates later told me that Slick50 has lawsuits against it for ruined engines. Apparently it contains paraffin and had a propensity for clogging things in some cases.

Follow-up from Dave U.:

Slick 50 contains PTFE which is (I am told) another name for Teflon which is also used on pots and pans. It's these particles which can plug up the passages. Quaker State and Pennzoil use as a base oil from Pennsylvania, which contains paraffin. They both at one time listed the paraffin on the side of the bottle.

My dad use to use Quaker State until he had an engine failure. This was back in the early 80's and Quaker State was also sued and paid out a lot of money for damages. Many people will swear by and at all of these new oil additives. I have used DuraLube in my 94 Dodge Dakota along with synthetic oil. I had a complete cylinder leak down check done when I bought it with 6,000 miles on it and again at 106,000 and all of the cylinders were within 1psi of the 6,000 mile test and I get 23.5 to 24 mpg. By the way I try to change the oil every 3,000 miles but that doesn't always happen, I do have a few 4,000 and two 5,000 mile changes in there and I have yet to add any oil between them.

I think it's safe to say that some engines will react well to these additives and others wont, why I don't know but your story is not the only one I have heard or experienced with friends. It all comes down to three things, how well the engine was taken care of over time what oil was used and how often it was changed. After my fathers experience and my own with Quaker State and Pennzoil you couldn't give a bottle of either one, personally I'd rather walk than use them, but that's me.

Also keep in mind buyer beware, by that I mean be careful about what you hear in regards to these additives, many of these companies are being sued right now over wild claims. I am only relating my experience. Ask other people you know AND trust to see what if any of these they have used and make an informed decision about whether you want to use these additives or not.

Addition from Eric:

Actually, Quaker State and Pennzoil no longer use any Pennsylvania crude. All comes from points south now. Actually, they are both owned by Shell now, so it will be interesting to see what comes of that. Teflon, made by Dupont, is not recommended by them to be used inside engines. To be honest, from what I have seen thru work, it is all pretty well snake oil. Lucas makes some petroleum based products which seem to work ok, but all the rest I have no faith in at all. If you want better oil, use synthetic.

Question from Adrian:

When posters mention STP, which product are you referring to? I hate to admit my ignorance but I am a little confused about oil designations, does anyone have a explanation?

Reply from Kne:

 For just a basic run down on oil designations Adrian, (forgive me if you already know this) basically, with 10w40 for instance, the 10 represents how thick or thin the oil is, or more technically it's resistance to flow, or viscosity. This is the oil's WEIGHT. The 40 represents additives or molecules that when hot, artificially make the oil flow "like" 40 weight, but it is not really the real thing. The lower the #, the thinner the oil, and visa-versa. So when you use 10w40 oil, you are actually using a 10 weight oil, and not even a whole quart, or a whole five quarts, as some of the oil is the additive, which may change flow characteristics, but does not do the "job" of oil, and when they break down you are left with dirty 10 weight oil. YUK! :-( Paul I believe said that he has had good luck with 20w50 in high mileage engines, but to my mind that's still a bit too thin, but far better than 10 weight (10w40) that most people use. I'd like to see him try some 30wt Castrol with a pint of STP, I believe he would find it "more better". (or "you" if you are reading this Paul.) Or straight 40wt. Yes, all the auto manufactures are using and recommending really light oils these days, usually 5w50's, (yuk, that's transmission fluid territory) but remember they have mileage quotas to meet, and don't care about the engine after the warranty is up, and would be glad to have the dealership rebuild it for you. You would think that all new cars would come with synthetic. (I believe the Synthetic web-page addresses that) Generally speaking, we used to run 10wt oil in a brand new engine, 20wt after it broke in, and 30wt when well broken in or in "mid-life" and beyond. So to me it's really strange to see people using 10w40 in well used or even well broken in engines...that's thin stuff, and the only real use of it to me is in super-cold climates during the winter. But I realize that these days for probably 80% or more of the people, 10w40 is the beginning and the end of "oil consciousness". Many times I have bought a old smoking Mopar for cheap, drained out the 10w40, and abra-kadabra.....the smoke has disappeared! ;-) Welllllll, there is much more to it, shear strength being one biggie, and that's why synthetics are an exception to the multi-weight rule, I believe synthetics have a very superior shear strength regardless, or less dependent on weight or viscosity, whereas the shear strength of dino-juice is more dependent on weight/viscosity I believe.

Question from Greg:

What do you think about STP lead substitute, "mystery oil" or similar products? It has been recommended with each fill up at my Chevron station.


From Kne:

Additives are neither junk nor wonder drug. At worst they don't do much. To say they are junk is unrealistic and uniformed. Sometimes they WILL make an engine run better. You have to experiment. Slick 50 will give a little extra protection on a well used motor. I've actually heard it eliminate slight amounts of bearing noise. Saw it happen. Was there. Done that. I've found that running synthetic oil is better than using additives, Slick 50, etc. If you think you need an additive, try synthetic first, you'll like it. If the engine uses too much oil to make that financially realistic, use straight weight oil of at least 30wt and some STP. Want to use some Slick 50? It won't hurt anything. STP will keep lifters pumped up better on a well used motor, and give some extra shear strength to the oil, and certainly won't hurt anything unless you use too much. It will never have to be "cleaned out" of the engine, you can drain it out, it's just an oil product. I have bought MANY a used car or truck for $100, $200 because they blew smoke real bad, drained out the 10W40, put in some straight 30 or 40, some STP, and got another 30,000 out of them. It's true. 3,000 miles is a good sensible oil-change. I don't think any of us are running our Imps in conditions that would call for more than that. Easily double that with synthetic. Change before storing for the winter, or before winter, regardless of mileage. On the cars I race, I change oil every 500 miles or sooner....maybe three or four miles if I only raced that car once that year. Not too practical on a driver, eh? Sorry, but I just have to say the following: With the exception of synthetic oil, or a brand new motor, I cannot understand why anyone would run muti-weight oil instead of a straight high quality single weight. Perhaps the middle of winter in a cold climate would be an exception. 10w40 oil is 10 weight oil with a bunch of ADDITIVES. Run a used or well used engine on 10wt oil and it's going to cost you 100,000 miles. But those in the "automotive industry" will recommend it without blinking. These are just things I know from 30 years of swapping engines, getting 300,000 miles out of engines, shade-tree mechanizing, working as a mechanic, making do with two and three hundred dollar cars, and countless times down the 1/4 mile track, getting greasy from head to toes, blood sweat and tears, not arm-chair "expertise", or 20 years pushing a pencil in the "automotive industry".

Follow-up from  Dick:

#1 point I agree on: Straight weight oil (I always use straight 30 weight) is the only oil to use in an older car. I am cautions about telling one of my kids with their brand new Japanese whiz bang turbocharged rocket to do that, though, since it would void the warranty, and might not have the right additives for a turbo. 

#2 point I agree on: you need thinner oil in winter, if you are so unfortunate as to live north of the 38th parallel. I guess 20W or even 10W would be my choice if so afflicted. 

As for cleaning out STP: I rebuild all my own engines, and quite a few for other people, and have been doing it since 1948 (yes, I was a teenager then). When STP came out, I began to notice a slimy feel to the crankcase gunk that was a b*t*h to get out, usually having to go through the hot tank numerous times to get the pores of the casting clean enough to accept the glyptal which I always use to keep the oil draining back quickly and keep the inside of the engine far cleaner, longer. If you don't bother with the glyptal, then I guess maybe the STP residue isn't too much of a problem, I just don't like it (personal preference). 

The reason I am so dead set against additives is they are a waste of money for sure, (another opinion) and some of them are causing damage, particularly the ones that include Teflon based additives. These do not pass through the smallest passages like liquid, they build up in tight places like lifters and cause oil starvation there. Briggs and Stratton, Cummins, Caterpillar, and the U.S.Gummint have all run tests coming to the same conclusion. DuPont sued to stop the use of Teflon in this way, specifically stating that it was an inappropriate use of their product, but lost the suit. You are going to ask for documentation of these statements, and I am not going to respond beyond saying that I have seen it, I probably could dig at least some of it out if I had to, but I have too many other fish to fry. Trust the Consumer's Union report on additives, they did their homework.  

I have no opinion of synthetic oil. They seem to work, I guess. I have never tried them, or worked on an engine that used them. If the car manufacturers recommend them, I would go along with it. I may be in the dark ages here, but aren't they very expensive? As for hands on experience, I've got some too. I've also spent time in industry, and in education, but I don't think either one is a substitute for learning by doing, other than perhaps an appreciation for scientific method and the laws of physics.

From Paul:

Having run several 318's to well past the 200K point without trouble...(preventative timing chain replacement was done)... and simply using name brand oil with frequent changes, I have wondered how anything could perform better. For daily drivers, (5th Avenue), I change at 2,500 to 3,000 miles which is 6 to eight times per year. For my Imperials, If I am driving them much at all, I try to change every 3 or 4 months even though the mileage may be only 1,000 miles or less. Most of the time I focus on one of the Imperials for several months and let the others sit in the garage. I have not worried about oil changes on the cars while in storage but I try not to let one go into storage with dirty oil. I have had each of my three Imperials for more than 20 years without engine problems or transmission either. I did rebuild the '66 Conv. engine when I first got it.

From Ron:

In my opinion and everyone has an opinion try Shell Rotella oil. !8 wheelers use it and I use it in all my older cars. I have very good luck with it but like any oil it is not what brand you use it is how often you change it. My preference is to run good quality oil with a good filter and change it often. Pay me now or pay me later sound familiar? I also make sure the thermostat is working properly. A cold engine builds sludge. I hate sludge!! This my opinion on oils and filter changes.

From Dick:

Anything that comes in a can and costs money will benefit your car's operation, by lightening the load from your wallet. There is no other benefit that I am aware of. The only exception I will make is that Alemite has an oil detergent booster called CD-2 which I have used with success to free up a sticky valve lifter. And of course, if you have a really badly worn engine that is unable to keep it's oil pressure up to a safe level when hot, STP will thicken the oil to boost the oil pressure for a while, but this is like putting a bandaid on a cancer - you're going to have to fix the problem, and soon. The various "Tune-up" and "engine cleaners" and other "mechanic in a bottle" products play on the fact that anyone can find anecdotal evidence for curing this and that by putting in some magic potion. If these potions are useful, they are already included in the compounding of quality motor oils, and adding more or different substances can only screw up the careful balancing of additives that some large company's room full of scientific experts devised. The "lead substitutes" are useless also, as far as I am concerned. I have heard recently that a study in England found most of them absolutely a waste of money, but one, and I don't recall the name, did have some benefit, very short lived and very expensive, but at least it did no damage. Save your money, folks. Put the $3.00 or so in a jar each time you are tempted to buy one of these products, and when you actually need to fix something, you will have more than enough to do it. I don't want to spend the rest of this week talking about this subject. Anyone who is interested in the additive subject will find there are enormous quantities of information readily available on the internet, and can find documents supporting any point of view one likes. I ask that you consider who had an ax to grind when reviewing this material. Start with the recent series in Skinned Knuckles on the subject of lubrication, if you want unbiased information. This series also will acquaint you with the differences in motor oils, which do exist, but are quite a lot less dramatic than you will here in the barber shop discussions. If you want to bypass all this discussion, go to your local oil distributor and buy Chevron RPM-DELO motor oil in whatever weight you prefer (I use SAE-30W, but I live in Southern California). You have to buy it in bulk or in 1 gallon bottles, but other than the synthetics, there is no better oil as far as I know.

From Brent:

Lead 'substitute' additives are unnecessary for any engine. The usual rationale for additives like this is to prevent wear to valve seats and faces, which is not a problem in normal driving by any stretch of the imagination. Valves and seats primarily wear under conditions when the engine is operated at extremely high speeds continuously (over 4000 rpm) and high temperature (wide open throttle). Damage is caused mostly because a stock valvetrain is not able to maintain close control of the valve motion due to inertial forces. What happens is after ~3500 rpm or so, the weight of the lifter, pushrod, rocker arm and valve begin to overwhelm the valve spring's ability to maintain contact between all the pieces, and ultimately the valve is dropped closed on the seat unsupported by the valvetrain. The speed this occurs varies between different engines, and depends upon a lot of things such as spring pressures, valve size, and the weight of the individual parts. As the valve springs lose tension from being cooked on top of the head over the years their pressure slowly decreases. At speeds closer to 4500 rpm, the valve may even bounce open again after being dropped on the seat. Heavy throttle increases exhaust temperatures to about triple the normal cruising temperatures. These high temperatures soften the valve and seat materials, making them wear much faster. If an engine is running extraordinarily hard (100+ mph) for LONG periods, wear occurs at a considerably accelerated rate. This is what wears seats and valves. Normal driving wears them extremely slowly, and most engines will never have a significant amount of valve/seat wear in their lifetime. Lead is thought to reduce this wear by many people, but in fact his a very minute effect upon it. Lead's attributes as a seat lubricant have been significantly overstated. In short, it has basically NO effect, certainly nothing that can be quantified. If your engine uses even a minute amount of oil past the valve guides or piston rings, you are getting many times the lubrication that lead ever afforded. YOU DO NOT NEED OR WANT LEAD. Lead has many other very strong NEGATIVE effects on your engine, and is a serious contaminant. Here is a link from the Rolls Royce Club of Australia, by K.E.Lee C.Eng., B.Sc. Hons., M.I.Mech.E., M.I.Mar.E., Chief Engineer, Power Train, Rolls-Royce Motor Cars Ltd (retired). It explains what lead does well, and the whole question of octane also. Regarding oils, use a 5W-30 with an 'SH' API Service rating like most new cars recommend. Its just fine, you pick your favorite brand.

Follow-up from Bob:

Thanks, it was interesting. On a prior post, Pennzoil was mentioned. I've had several mechanics tell me "anything but Pennzoil", claiming it produces more sludge than other oils. There are postings about oils and synthetic oils on the web. One is: A few months ago I found a site that had a comparison of oil filters. It's been removed because of a threat of legal action! It was at: If I remember correctly, the differences found confirmed similar comparisons I've read in auto club magazines - the popular orange filter may not be the best. 

Question from David:

I removed my valve covers today, to replace a leaking valve cover gasket, and found the entire inside of the valve covers (and rocker arms, valve springs, push rods, top surface of heads...) covered in a thick crusty black gunk. I just bought the car, and am still in the process of registration, and titling, so the only times I've actually driven her were: a short test drive before I bought her, and off the trailer into my driveway, when the guy delivered her. The engine ran smooth and strong both times. Common sense would tell me that it's 35 years worth of oil splattered around in there then caked, and charred with the heat of the engine. The problem is I've never seen anything like this (at least not this extreme), when pulling valve covers off any of my other cars. I'm in the process of cleaning the covers, and plan to clean the top end of my heads, before replacing the covers. I'm worried though, that this same buildup could be throughout the motor's oil passages, and can only imagine the damage this could cause down the road. I'm curious if anyone knows what might cause it to be this extreme( 1/8"-1/4" thick coating every surface under the valve covers), whether or not I should be concerned about the inner workings of the engine, an if there's any way to remove this buildup from the inner oil passages short of pulling the engine apart, and rebuilding it. Are there any oil additives, or other means by which to flush out any crud that might be clogging my engines arteries?


From Kne:

Wow...don't usually see this anymore. This used to be more common with non-detergent oils, but it is usually a result of infrequent oil changes and a hot running engine, or an engine that has overheated periodically with in- frequent (or none) oil changes. Again, non detergent oil aggravates the situation. I would also say that the crud, unfortunately, is probably throughout most of the rest of the engine. I hope someone else can add more to this, but here are my thoughts. Pull the rocker arms and clean them and the shafts and the valve covers for sure, and of course you know you are in for frequent oil changes now if you use engine "as is". I have had more than a few daily-drivers, picked up for cheap, in this condition, so I just drove them "as is", and didn't have any problems. The crud, of course, does not effect the performance of the engine. The old wives tale, when this was more common, was not to switch to detergent oil, as that would break the crud loose and cause problems. Makes sense, but I never tried it. What I personally would do, because I pull engines often and I'm set up to do that, if it's a good running engine and does not need rebuilding, I'd pull it, put it on the engine stand, strip it down to the short-block, and then just start scraping and cleaning with rags, gas, screw-drivers and scrapers. If you leave it as-is, I guess the big fear is that a chunk breaks loose and plugs an oil passage. I don't think chunks falling into the pan are a big problem, as there is a screen on the pick up, so that actual chunks are not going to go through the pump. When you have the rocker arm shafts off, take a good bright pen-light and look down the passage that feeds oil to the shaft. That should give you an idea as to whether the passages are anything like the inside surfaces of the engine. My gut-feeling is that the passages may be o.k., and most of the crud is on the inside surfaces where the oil was not moving so fast, and had time to bake on. (no PCV also aggravates this problem) If the passage looks o.k., I would leave the engine alone for a while, change oil and filter often. It would be really good to find out what kind of oil was being used in it before you got it. It might still be on non-detergent, if so, you might want to stick with that if the "old-wives" tales are true. I'd be surprised though, most people are not aware of detergent/non-detergent oils, and just have the mini-lube put in their 10-40. So it's probably running on detergent oil now anyhow. If you feel real brave, give the engine a couple of treatments with oil-flush, change oil every 500 miles for a time and see what happens. Again, if the oil passages are not actually plugged, I don't think you will be in danger of losing oil pressure, the problem will be a large amount of abrasive material going through the oil pump, some passing through the filter. Get the best filters you can, change oil as often as it get black looking, even if it's only a couple of hundred miles. Oil pump is not hard to change on the big block, so I would not worry too much about trashing it. Be sure to use a straight grade oil of reasonable weight, 30wt, while all this is going on. My Mopars all like Castrol 30wt. (actually I'm using Mobil 1 al ot, but I don't think you want to do a Mobil 1 oil change every couple of hundred miles!!!) ($$$$)

From Dick:

You will get a lot of advice on this one, and you will have to sort which sounds right to you, but I would not try any kind of detergent booster or "motor flush" stuff because you are likely to let loose more crud than your oil filter can handle. The crud that is stuck on tight is not on parts that have to run in contact with other parts, and it will not do any more damage than has already occurred unless it breaks loose and begins to circulate with the oil. My advice is to clean up what you can get at easily, and leave the rest alone until you decide to rebuild the engine, then have it hot tanked or better yet take the bare block to a metal "laundry" place and have it stripped all the way down to the casting. The engine will possibly continue to run just fine the way it is. The cause would most likely be a failure of the PCV system, possibly compounded by the way the car was driven (many short trips) and/or by using very cheap oil and long to never change intervals.

From Peter:

I have run into that situation on a V6 GM (wife's Olds Cierra). When we bought the car (used w/86K), it ran good. After a couple years, I replaced the valve cover gaskets. When I removed them, the crud was SO thick I literally could NOT see the valve springs. I mean, there was OVER 1" of crud everywhere. I simply could not believe it was still running. We nicknamed it "Sludgy the Whale". Soon after that, it developed a rod knock, so I replaced the engine. When I disassembled the old engine, the lifter galley was literally bridged with to bank.. I don't think the oil was EVER replaced for the original 86K. I have used Mobil One since. Now with another 80K, the heads still look new. You might want to try one of those engine flush treatments (Rislone), but it may take several treatments to dissolve just some of that sludge. Of course, scrape and remove as much of it as you can from the heads before you continue.

From Rick:

What I do is clean out the valve covers good and clean around the rockers and valves stems (don't touch the seals on the valves inside the springs) just the big pieces of crud on the head. Then I get a double oil filter (Fram) 4 quarts of Walmart oil and a quart of tranny fluid and do the oil change.  Do it 5 or 6 time every 100 miles or so.  When you do the oil changes check and see. The oil should start to get all the crud out of the motor.  The tranny fluid cuts the crud from the parts and ends up in the oil pan and you drain it out.  The only problem is some times if the valve seals are bad the tranny fluid will make them fall apart and you will have to replace them.  This is what I do and had good luck with it.  

From Ron:

For the most part I agree with what Dick says here, Motor flush or any strong solvent WILL do more DAMAGE than good simply because very large chunks of this CRUD will be loosened and wind up in the oil pump sump clogging the screen and starving the engine of oil. Before you start scraping this CRUD loose be sure not to cause the same condition by allowing this crud to fall into the engine, I use a shop vac to suck up what I scrape off, another way would be to stuff rags into the return holes and pushrod holes, but this is a less desirable method. One word of caution, if your crankcase smells like gasoline or if there is a gas leak anywhere under the hood, stop the leak, and clear the fumes out BEFORE using a shop vac. most models move the discharge air thru the motor and the arching of the motor brushes could ignite or explode the vapors. Back to what you can and NEED to do, after cleaning this mess up and reassembling everything, use a quality oil no heaver than 10w40, and a MILD detergent additive. I have found that Rislone or CD2 Detergent added at oil change time helps to dissolve most of the crud that is already in the oil pan and in the pickup screen. If this engine runs good and has sufficient oil pressure, you then need to pay close attention to future oil changes, and keep an eye on oil pressure, a sure sign of a clogging up oil pump sump screen is that oil pressure DROPS as RPM INCREASES. I would prescribe the following continuing treatment; No high engine revs, or highway driving, Change the oil/filter and add more Rislone or CD2 every 500 miles until the oil stays fairly clean for 250 miles, than at 1000 miles more do it again, than your probably OK to go for 2000-3000 mile intervals, and RESUME what this car was built for HIGHWAY CRUISING! Also another problem that causes this crud buildup in addition to what Dick mentioned is HEAT, check for proper coolant temperature and check that the exhaust crossover butterfly valve (heat riser) isn't stuck closed. Those pesky heat risers have BAKED a lot of overdue for a change oil into CRUD !

Question from Bill:

 Anybody know if there is any problem with using one of the very good top of the line synthetic oils in any of these old engines? Any additives anyone would recommend? 


From Kne:

 I have tried some synthetic oil (Mobil 1) in my other high mileage car, the Replica BluesMobile, and it worked fine, but I can't afford a lot of that, so when it uses a quart I add some Castrol 30wt, and more Mobil 1 some of the time if I have an extra nickel-ninety-eight in my pockets. Oil consumption does seem to be less with the synthetic. I believe that the old BluesMobile has had just about every additive poured down it's crank-case at one time or another, and they all seem to be about the same, no wonder additives that I have ever found, so I basically just stay with straight grade oil and STP these days. On Synthetic I use the heaviest grade, which I think is 15w50. But it is expensive, and you may find the price of burning it is not worth the advantages of it. Castrol 30wt is only $14 a case here, so that gives me an oil change and plenty of "add-a-quarts" for the whole fleet. Anyhow don't waste you money or engine using light multi-grade oils in a high mileage motor, although Synthetics seem to be the exception to that rule.

From Tom:

 From Tom:  Here's what made me start using synthetic. I had a beat-down '78 magnum with around 170K miles on it. On the way to work I made about a 10 mile x-way run at about 80. (Roads are dead in Detroit ghettos at 5 AM, Doesn't this prove my confidence in late 70's Mopars?) Anyways, When I'd get off the x-way and stop for the first light, the oil pressure would drop quite a bit on the gauge. Only revving the engine would keep it up. Then I started running Mobil 1 (or any other syn.) Under the same conditions, the pressure would still drop a little (as is normal) but not nearly as much as before. Obviously, it maintains its viscosity (thickness) better than regular oil. I agree however, that it would be too expensive to run in an oil burner/leaker.

From Bill:

You will get many different answers and who knows which is right. The last article I read about oil was in Skinned Knuckles, I believe. They did recommend any additives at all. Something to do with the oil itself being specially formulated and adding anything would defeat the purpose. In my car, I switched to a synthetic blend and it started smoking right away. Just a little too warn out I guess, so I am going to switch back to straight 30 weight.

From Bob:

I like Shell's Rotella oil.  I think it is synthetic...

Follow-up from Curt:

 Shell Rotella is not a synthetic motor oil at all. In diesels the oil gets loaded up with carbon very quickly and starts breaking down very quickly and the turbocharger adds additional stress to the motor oil. The Rotella does not break down as quickly as conventional motor oils since it has additives to combat the soot. We go to Sam's Club and buy it by the case since it takes 2 gallons at every oil change (which on the 617 diesel should be at 5k intervals). If you have any questions on the clacker send me a line.  Soot really is not a problem with gasoline engines since the fuel they burn does not contain sulfur as in diesel fuel. For higher mileage gasoline engines it seems any high quality conventional motor oil does the trick as well as synthetic motor oils, which I've installed in our 3 show cars.

Question from Bob:

Seems to me, many years ago a refinery put out a premium oil called Royal Purple Triton. But, I've since long forgotten who it was. Anybody remember this product?

Reply from Mike

That'd be Union Oil of California, aka Union 76, later known as Unocal (boo... hiss... ) Until I am convinced that they are no longer insisting on crushing vintage cars without allowing part removal first, I refuse to buy anything that might come from them.  Marilyn Monroe once appeared in a 76 Royal Triton commercial driving a '60 convertible.


Has anyone ever used Kendall oil and have any opinions on it?


From Coby:

Kendall is the worst oil on the market I would use Recycled Wal - Mart oil before I put Kendall in anything I own!!! Kendall is so DIRTY! Have you ever gone through an engine that had Kendall ran through it?? You would not run Kendall if you looked at the engine components I've seen! Valvoline VR1 Synthetic 20w50 Racing in everything except my 99 Chevy Truck (10w30)


I work at a Wal-Mart and we used to sale Kendall oil. Kendall was not selling very well and we finally put it on clearance. I have been using Pennzoil 10-40 for the past 15 years. A friend of mine was telling me that Pennzoil will turn the inside of your engine black. He told me to use Castrol 10-40 on my Imperial and New Yorker. Have some of you heard the same thing about Pennzoil?

 Follow-up from Kne:

I like Castrol, but I sure would not run oil as thin as that (10w40) in an Imp or New Yorker. Stick with straight 30wt unless the engine has less than 5,000 miles on it. The only thing I noticed back when I still would sometimes use Pennzoil is that an engine would smoke more and consume it faster than Valvoline, Havoline or Castrol.

Follow-up from Barbara:

My husband put Penzoil into his '65 Belvedere 383 once. It burned out about a quart in 500 miles. The car hadn't burned out before and didn't again when he returned to Valvoline. He won't even consider using it again. The car was 3 years old at the time - long before synthetics were available to the 'common' man.

Follow-up from My413:

YESYESYSEYRSYESYESYES it contains phenolic resin which is wax!!!  What happens to wax when it gets hot?   Everybody has got their preferences.  I've tried them all, but you never know what'll happen in your motor.   Here are my opinions:

Kendall: better than any std or synthetic oil I've found. 

wix: better filtering, won't deteriorate. 

k&n. reusable filters. 

stp fuel cleaners. only thing that actually cleans. 

cd-2. best thing that actually seals rings and leaks. but doesn't clean out the rings on an old motor. Usually that could be holding it together.

Don't use Pennzoil or Prolong (eats bearings at high revs.) or Fram (deteriorates too easily).  Don't use anything that sells good at Wal-Mart.  Go to a small parts store. They'll tell ya what's up!!

Question from Mike:

Just wondering what everyone's thoughts on using slick 50 or some other thing like that in a 440 ....  I'm thinking about doing that to mine.. ( 100,150 miles) any thoughts?


From Marcus:

DO NOT DO IT!!!!!!!!!! Please read the consent decree the FTC got out of the owners of the company , they could not substantiate the claims. Slick 50 will actually reduce the life of your engine by up to 30%, the stuff was so bad Dupont at one point, refused to sell Teflon to the manufacturers of Slick 50. Your engine would have to reach 1200 degrees for the Teflon to bond to the surface.

From Chris:

Just one: Don't bother. There's no reason that with proper oil changes (by time and mileage), good maintenance and frequent exercise (if it's not a daily driver) that your 440 won't go for another 100,000 miles without using additives with virtually no clinical or field proof that they do any good. In fact, some say the Teflon can clog up the smaller passages in the block, though I've never heard of Slick 50 doing any harm either. A 440 is a long-lasting motor. Good basic care are about all it should ever ask for.

From Mikey:

When I had a fleet of over 30 assorted vehicles to maintain ( lpg powered, gas, diesel ) we looked hard and long at a lot of these products. We tried to find as much objective info as possible, and we did try a few. Money wasn't a problem, our goal was to keep this stuff on the road 24-7 with only scheduled maintenance. I don't recommend Teflon, of any kind. nor graphite. I won't say that they will harm your engine but I doubt very much they will give it an ounce more life or power. There are a few products, I honestly cant remember the names, but they are not Teflon, they don't recommend or advertise emptying your pan and running around. They aren't cheap either, but in every vehicle we used them in we had idle speeds increase and vacuum gauge readings go up, with no other changes. this stuff was by the gallon, and it was $$$. We added a few ounces at each oil change. But to be honest, and for what its worth ....oil is cheaper. buy it and change it often. You can bank on it, that and drive the car enough to boil all the condensation out of it now and then.  We have used delo 400 15-40 forever, with over 250000 on my barracuda (318) and over 100000 on my charger.(440) and 37 years on the imperial - its never been opened below the valve covers or intake.

From Robert:

DuPont said it doesn't work. NASA's Lewis Research Center says it doesn't work and has the potential to cause damage. The University of Utah found that it impeded engine oil flow and *increased* engine wear. Some of the additives also have the potential to harm catalytic converters due to high zinc content. If you want lots of information, see the following sites: Snake Oil Explained:   Note in particular DuPont's reaction; DuPont was the original supplier of PTFE for these additives and stood to make money off of them - if they worked. DuPont said they don't work. Here are some of the FTC complaints regarding Slick 50, STP, and Valvoline engine additives. Their advertising was found to be false and misleading:  

From Dan:

In my mind, the FTC has proved its case.  The heart of the FTC's action is that the "oil additive" products work no better than engine oil at any of
their claims.

Put in your favorite oil additive, or simply search for "oil additive", and see that every major manufacturer of oil additive has signed an agreement with the FTC in which they will not make claims that their products reduce engine wear at startup, coat engine parts, extend engine life, etc.

Prolong, Slick 50, DuraLube, etc., they're all here.  Not one manufacturer was willing to back up their claims!

I quote from Prolong's agreement below.  Prolong runs those infomercials with guys throwing dirt on an engine while its running.

Prolong's Order:

IT IS ORDERED that respondent, directly or through any corporation, subsidiary, division, or other device, in connection with the labeling, advertising, promotion, offering for sale, sale, or distribution of Prolong Engine Treatment Concentrate or any other product for use in a motor vehicle, in or affecting commerce, shall not make any representation, in any manner, expressly or by implication, that:

a. Compared to motor oil alone, use of such product:

(1) Reduces engine wear at start-up; or

(2) Extends the duration of engine life, under any or all circumstances or conditions or by any quantitative figure, unless, at the time the representation is made, respondent possesses and relies upon competent and reliable scientific evidence that substantiates the representation.

b. Use of such product:

(1) Reduces corrosion in engines; or

(2) Protects against engine breakdowns, under any or all circumstances or conditions or by any quantitative figure, unless, at the time the representation is made, respondent possesses and relies upon competent and reliable scientific evidence that substantiates the representation.

c. Benefits that may be achieved through use of such product in race cars or under racing conditions will be achieved in ordinary automobiles in conventional use, unless, at the time the representation is made, respondent possesses and relies upon competent and reliable scientific evidence that substantiates the representation.

Question from Mike:

I have a high mileage engine.  What type and weight of oil is best to prolong the age of my motor?


From Richard:

Having worn down a main bearing or two, I generally run 10/40 year round. When the oil pressure starts dropping (every 100,000 miles or so) I'll run 20/50 in the summer months. When the mains are well past their intended service life, pour in the STP.   I once ran a 360 on 20/50 AND STP through the winter (guessing the 88,000 on the speedo was actually 188,000). It started just fine even on the coldest days, and had decent oil pressure. It blew up in early spring, but feels much better now.   As for brand names, I've been using Valvoline for years (no clue why) and don't have any complaints.  An engine rebuilder once told me that Quaker State was the worst oil he'd ever seen. His opinion was that every Quaker State run engine he'd ever rebuild was caked with sludgy build-up.

From Bill:

I have heard the same thing about Pennzoil. Actually I now use both in different vehicles. I believe the theory about the colder the climate the lower the number, etc., except the leaker/burner where a heavy weight goes farther. Anyway, it seems like years ago I was told all oils come from the same place, below the ground. Is there that much differences in just the additives? If so, then a cheap generic oil with a good additive, Wynns, STP, Mystery Oil should be the way to go, right? Just my thought!! One more thing if someone knows. Is Dexron II and Dexron III the same thing? If not, can they be mixed? My Jeep calls for the II in the transfer case and I need to add some. I have III on the shelf. Sorry, if I've drifted too far away from the Imperial motif but I'm all Mopar.

From Curt:

 For higher mileage gasoline engines it seems any high quality conventional motor oil does the trick as well as synthetic motor oils, which I've installed in our 3 show cars.

Question from Norm:

Has anyone ever used "Sea Foam" engine additive?

Reply from Clay

I have always used SeaFoam combustion chamber cleaner with good results also. 1/2 -3/4 a can down the throat of the carb until it stalls. Then I let the car sit a couple of hours before I start it up again. Made my 67 purr like a kitten.  Pinging is the main reason I use Seafoam. I do try to use it close to oil change time. It almost always makes a engine idle smoother. Don't have a clue why.  I use it about twice a year.

Question from Timothy:

I questioned using tranny fluid to clean the sludge out of a big block Chrysler and was advised it is a no! no! Tranny fluid has additives that swell seals and can rupture seals in a engine. Advise if this is true.


From Bruno:

I've been adding a quart of ATF to noisy engines for years.  I run it till the valve noise clears up and for a few days more then replace the oil and filter.  I have never had any negative results.

From Jeff:

This is not at all true. The "seals" in your engine are not different from those in your trans. Trans fluid is a very high detergent oil. BTW, it is dyed red so that leaks can be differentiated from other fluids. When I was younger, I wrote to Pennzoil engineers to ask about the use of trans fluid for cleaning engines. They specifically said that while it would cause no damage, they would like to recommend one of their specialized products. Well, of course! That was the answer I needed to lend me assurance. Keep in mind that products like Shaler's Rislone is an excellent high detergent mineral oil that can be used for cleaning, too. I like it because it replaces a quart of oil, a very slight savings if you're going to use an additive anyway. That all being said, do you really want to clean your engine? I have NEVER had an engine problem attributed to sludge, with the exception of poor oil supply to the top end of old Ford Y-blocks which had not had oil changed frequently. I have seen engine cleaners LOOSEN amounts of sludge that did end up plugging up the oil pickup or passages and caused oil starvation and engine failure. If your engine is very sludgy, DO NOT use engine oil supplements to clean it. Enjoy the miles you have left in it as it is. 

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