Originally Posted By: turnbowm
Originally Posted By: BrocLuno
...And if you don't believe in residual film, what do you actually think keeps the metal parts apart for the first minute or two of operation? The parts I described never see "pumped oil" and they are the ones taking the beating ... They need something like 2,300 RPM to get enough sling oil. So the cold start idle time and easy drive off is all about residual oil film!
You and 540Rat seem to be on the same page regarding the importance of oil film strength in startup wear. I totally agree.
I don't see it that way.
If you pull an engine down, even if it's been sitting for many months, you will get covered in oil, it's held there via capillary action and doesn't drain down like some proponents would have you believe...so for that first crank and initial operation, there's a reasonable amount of VERY thick oil proviiding hydrodynamic lubrication for bearings and skirts...Plus the tribofilm from last time it was operated is still there.
RAT's only testing something that is a bit like a solid lifter/cam interface...doesn't apply to bearings and pistons skirts (and probably not much to do with rings either).