Guys,
there is a company that does research on this topic:
"performance unlimited", Hartford, Wisconsin (262) 673-4077
They placed a nice chart from AATCorp.
The bearings are about 75°F hotter than the
oil in the pan. Bearings are supposed to wipe out at 375°F.
That is 300°F in the pan.
Best mileage is at 195°F in the pan. Unfortunately they do not list a value for best performance.
Sorry, I do not have a weblink for this company.
Dominik (95%?)