At what temperature does piston aircraft engine oil break down?
This is not the same as the maximum oil sump temperature allowed for your engine. Both Lycoming and Continental recommend a maximum oil temperature of around 245°F.
Running at 245° may be OK during break-in or during climb out, but I do not recommend running continuously at cruise condition at this temperature after your engine is broken-in.
In many aircraft, the only indication of how your engine is operating is the oil temperature. A 245° oil sump temperature is an indication of incorrect tuning or engine installation. [Read more…]