Hey Duke another oil question

[Robert Margolies (32164)]

After reading enough of the science behind the oil controversy for flat tappet cams, I was about to buy a suppy of Shell Rotella CI-4plus when a mechanic friend mentioned that diesel engines were never designed for the RPM's that high performance gas engines were and that might be an issue with the oil. He thought it was better to go with a true racing oil such as Valvoline. Give me your take one more time and I am buying my supply for both Corvettes and my LS6 Chevelle. Thanks

[Duke Williams (22045)]

Re: Hey Duke another oil question

I've never heard this myth before. Your mechanic should stick to changing parts!

C and S category oils use the same base stocks - a blend of Group I, II, and III. The primary difference between the C and S service categories is the additive package as discussed in GREAT detail in the archives along with the base stocks.

Many racing oils that are designed for mild temperature cold starts and high operating temperatures are 20W-50, and because their winter viscosity grade is above 10W, they aren't limited in phosphorous content, so they can still be labeled SM.

Of course, anything labeled "racing oil" is going to cost, and a good racing oil is probably closer to CI-4 in additive content than SM oils with a winter grade of 10W or less.

Any enterprising individual could buy 15W-40 CI-4 oil in bulk, package it in bottles labeled "racing oil" and have a good a product as any other available "racing oil."

Duke

[Robert Margolies (32164)]

Re: Hey Duke another oil question

Thanks Duke.I am going to get my supply of Rotella tomorrow for all three cars.

[Mike McKown]

Just a thought,

He's probably thinking the diesel oil will foam at high rpm. Rotella protects against that.

[Robert Margolies (32164)]

Re: Just a thought,

Thanks for your opinion but I am in complete agreement with Duke and I don;t believe that any brand is better then any other. What I have found interesting though is that the local PepBoys has CI-4 oil available in gallon containers in all brands, and they have alot of it. I was under the impression the CI-4 was being replaced with CJ-4. In any event it is readily available and I picked up enough for a couple of years worth of oil changes in all three cars.

[Mike McKown]

Re: Just a thought,

Well, I'm not in disagreement with anybody. Just trying to be nice to your "mechanic".

[Robert Margolies (32164)]

Re: Just a thought,

Mike, The guy in question is a mechanic but not mine. After seeing your original post I called him and asked if that was what he was thinking and he said that was one issue and other being the added sulfur in most HD diesel oils he thought was not what he would want to put in a high perfromance gas engine.

[Duke Williams (22045)]

Re: Just a thought,

C-category oils DO NOT have "added sulfur"! In fact, just the opposite - they have added acid neutralizers to control sulphur combustion byproducts! CI-4 oils are designed for use with high sulphur diesel fuels, so they have a high dose of acid neutralizers to neutralize sulfuric acid that forms from the SO2 and H2O combustion byproducts. Since gasoline has much lower sulphur content than older high sulfur diesel fuels, sulfuric acid is much less of an issue, but the "excess" acid neutralizers do no harm. In fact, they provide added corrosion protection in case you forget to change your oil on a reasonable schedule.

CJ-4 oils have less acid neutralizers because they are designed for use with the new low sulphur diesel fuels, which reduce sulfur to a very low level - on the order of gasoline, so the reduced acid neutralizers in CJ-4 are not an issue on vintage gasoline engines, and CJ-4 still has more acid neutralizers than SM.

Most modern HD diesel engines are turbocharged, and turbochargers are tough on oil, which places a premium on shear stability, oxidation resistance, and anti-foaming.

In every API certification test the requirements for C-category oils are equal to or tougher than for S-category oils.

Duke

[Dale Schafer (48165)]

Re: Just a thought,

For a brand recomendation for oil at our parts store, we said "the best oil is clean oil". We saw customers with 10 to 20 thousand miles on their oil change wanting to know what brand was best to buy. Dale

[Robert Margolies (32164)]

Re: Just a thought,

Thanks Duke, I need no further convincing. Just got back with my supply of CI-4 oil.

[Clem Zahrobsky (45134)]

my experience with series 3 diesel engine oil

i built a 427 BBC race engine for a circle track race car and at the first oil change the owner used "series 3" diesel engine oil because he bought it by the drum for his equiptment. the engine completely wore out in 2 nights of racing. i called GULF research at the time and they told me that series 3 diesel engine oil was not made for high RMP and high pressure from race camshaft springs. this happened the 80s BUT it did happen

[Duke Williams (22045)]

Re: my experience with series 3 diesel engine oil

I've never heard of "series 3" diesel engine oil, and don't know what it is, but I doesn't sound like and API specification.

Back in the sixties diesel engine oils carried ratings like "DG", and many motor oils were dual rated. "MS" was an early rating for detergent spark ignition oils.

The current "S" and "C" ratings began in the seventies IIRC.

Duke

[Dick Whittington (8804)]

Re: my experience with series 3 diesel engine oil

Duke, there was a series three rating at one time (very early '60's maybe)I was somewhere along the time that you purchased your diesel oils by MIL specs such as MIL spec 2104-B etc. I will look at the old Lubrication Engineering? books when I can find them.