torture test oil

[XWrench3]

I really do not know where the best place to post this is, but this seemed like the best choice. i spent my career as a motorcycle / snowmobile / atv wrench. during that time, i came across a total of 3 engines, that had been so severely overheated, that the engine oil (conventional motor oil) had been "cooked" into what best resembles grease. all 3 of these engines were air cooled, and strangely enough, all 3 were in the 200cc to 300cc displacement range, with 2 of them being 250cc. i remember the story on the last two of them, but the other one was so long ago, i really do not recall what happened. one was an atv, that the owner was using as a tractor, trying to work up ground so he could plant a deer food plot. the other was a motorcycle, that a conservation officer, who had never ridden a motorcycle before, used in pursuit of a poacher. he ran the bike in first gear, wide open, until the engine seized. never riding, or driving anything with a manual transmission, he did not know he needed to shift.

what I would like to know, is how hot motor oil needs to be, before it "cooks" into a solidified grease like substance. since this is a racing forum,and motor oil gets pushed pretty hard in racing applications, i thought someone might have an idea.

[XWrench3]

well, from what i can find on Wiki, refining grease from raw petroleum crude takes place in the 350-400 degree temperature range. so i would have to think that the same temperatures would apply in this application. hopefully, nothing i operate will ever near those kinds of temps during operation. i would have to believe that liquid cooling of an engine would also help a lot. since the normal temperature of the engine oil right now is in the 210 degree range, i should be very safe for now, unless something drastic happens.

[Black Lotus]

Just somethoughts----
I recall reading that Porsche, with their aircooled engines ran out of cooling capacity with their fans and fins layout, therefore they had to make up any cooling shortfall by cooling the oil with larger and larger oil coolers.
So that could help keep your head temps down, if that worried you.
Apparently Nascar engines are running about 240* F, up to 270*F oil temps.
Corvair aircooled engines ran from 210- 250*F oil temps.
My own car, water cooled, that has an oil temp gauge on it will see 175*F climbing over a mountain pass at 70 MPH. It uses two oil coolers routed in series, inside ducts (OEM).
So the upper safe limit in a 9,000 RPM racing engine seems to be about 270*F.
Would think that any engine with a pressurised oiling system could tack on an oil cooler and work temps out that way.