Quote:
Originally Posted by CSG Mike
What race team allows for 320F?
Have you ever seen the rod bearings on a S65 with that kind of use with and without a properly sized oil cooler?
Why do you think that BMW went to a thinner oil with more bearing load (boost)?
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Can’t remember the teams. Discussion was had at a GT World Endurance Championship Race in NL and earlier with the engineering sides at M1, Motul, and Liqui Moly. The latter was an aside conversation while selecting industrial lubricants for professional use.
Bearing issues with the S65 are independent of the oil temps. They are theoretically related to insufficient bearing clearance, and yes I’ve seen hundreds of examples. Extra clearanced bearings often showed normal or minimal wear. OEM spec always showed excessive wear including ones operated at temps believed to be the magic temps discussed here.
I assume BMW engineered robust cooling to accommodate the lower viscosity needed to meet fuel economy goals for situations where boosted M cars were going to be operated at full or close to full pace. Oil temps in the S55 rarely deviated much street to track in mine and others experience.
If one were to run an FA20 at full race pace then a cooler may make sense, but not for the street and not for us weekend warriors. And if in race pace temps are not going north of say 280F I’d question the need for one more failure point with adding a cooler. Oils and engines can handle these temps today unless the flat engines have a weakness that other designs don’t. My educated opinion of course.