You are not getting it. How much hotter do you think the case is 1" above
the oil level? About the same. The important part of this is that you are
adding more heat by raising the oil level because the crank is thrashing
about in the oil. That is why the oil is vented overboard when you fill
the case. Try different oil levels in your airplane and see for yourself.
You probably won't be able to measure the difference unless you have a
digital oil temp guage. It also take power to thrash that crank through the
oil, power that would go into turning your prop otherwise. This whole issue
is one reason why race cars use dry sump lubrication systems.

Mike
MU-2


"Matt Whiting" wrote in message
...
Mike Rapoport wrote:

The oil level is about 1" higher and the case is highly conductive.

So, 1" times the circumference of the case is a fair bit of area and
with a highly thermally conductive Al case, that will reject additional
heat to be sure.


Matt