Originally Posted by ChrisSlicks

The oil temp is largely irrelevant, however it is an indicator of what the engine block and head temperatures are at, as well as intake temperatures which will have an effect on combustion. So yes, there is a correlation but it is not direct.

The interesting thing I discovered was that on track straight-line speed was roughly the same after 20 mins as it was in the beginning of the session, however climbing hills under load there was a noticeable loss of power especially in the lower RPM band. Would be interested to see why the low RPM is effected more.