brand-neutral oil question - performance-related

[fest3er]

This is a brand-neutral oil question. I'm hoping folks with extensive high-performance experience can chime in with useful info.

The Cummins B-series requires 15W40 oil for ordinary operational usage. I don't know what the Powerstroke and Duramax require, but I would think it'd be quite similar.

The question relates to high-HP racing/pulling operation. Given that the 15W40 oil provides a cushion of oil on which the moving parts ride, at what level of torque/HP does 15W40 become too thin to provide adequate lubrication?

Considering that drag racers often use 20W50 in their engines, it occurred to me that perhaps the high HP diesel guys might want to consider increasing their oil viscosity. Or is this question of viscosity in performance diesels a non-issue?

N

 

[BarryG]

Funny you mention this. Keeping this neutral I just recieved a catalog in the mail the other day and low and behold what did I see in it, 20w-50 diesel engine oil. With some advertising about high performance racing diesel oil. Have never seen it before. Can't answer your question as to whether it is needed or not though.

 

[fest3er]

TTT

 

[Bob Wagner]

try posting this in the competition forum

 

[HEMI®Dart]

My 2 cents:



15W-40 is plenty heavy enough for even the most extreme B5. 9 CTD.



Is this true? I dunno

 

[Steve M]

One more thing to consider is, while the oil needs to be thick enough to provide the cushion, it also needs to be thin enough to flow through the bearings fast enough to carry the heat away and give a new charge of oil on each bearing load. Otherwise the oil will overheat and coke in the bearings. Heat transfer is oil's "other job".

Being non brand specific, there's some quart bottles of oil on the shelves at our local auto parts store that claim to be fully synthetic 20w-50 and is turbo diesel rated. "C" for combustion and "S" for spark engines. I don't know if warranty is a concern with highly modified engines with regards to what the owner's manual calls for.

 

[nickleinonen]

"C" for combustion and "S" for spark engines

the "C" stands for compression ignition engines

the "S" stands for spark ignition engines



i don't know if you want a heavy oil drag racing. that makes more friction in the engine and less HP is made. i have seen full synthetic oils that are designed for drag racing [royal purple i think] that is 0w10. them pro's are tearing the lowers of the engine out every run pretty much.

 

[curatchko]

I have a good amount of experience in building max effort drag race engines and I'll say that we don't typically use 20/50 oil in them. Typically if maximum power is the goal we will use a 0 weight oil... . So I wouldnt' suggest that viscosity is based on engine load.



Much is dependant on internal clearances... . tight clearances can tolerate thin oil, king kong clearances will need thick oil.



Other issues might include oil temps... . Our cummins engines have a turbo that is oil cooled which is part of the viscosity requirement we have.



The other issue with our engines is that from what I can recall, we have pretty large bearing clearances in these things... . (relatively)... .



Chris

 

[Turbo Tim 1]

Originally posted by nickleinonen

the "C" stands for compression ignition engines

the "S" stands for spark ignition engines

Now in the voice of Cliff from Cheers, now that theres a common misconception among gear heads, the S actually stands for "Service" and the C stand for "Commercial". The API has a good site with a butt ton of information on it. That is where the S and C information came from.

 

[Steve M]

Shoot... I was going by what I read in and earlier TDR rag and I even got that wrong.

 

[Doc Tinker]

I was just thinking that RPM might have more bearing on why heavier oil is used in gas performance applications.



Doc