[Piotrsko]

You do kinda want to keep the internal parts temperatures below 250 because at that temp the oil starts to break down and lose lubrication factors.

Typically at the rod to piston junction, but I don't have current technology information and have no way to measure that. Historically rod bearings fail from heat/lube failure.

Additionally, since there seems to be a dearth of information, some experimentation needs to be performed because typically most ICE favor different operational temperature efficiency.

I am 100% in favor of grill block, test, modify, test rinse, repeat until trends show you went too far or oil temps get to be about 225f, or the smoke point of whatever oil you use. Smoke point should be available on the mfr website.