Roger Long wrote:

Woah! It sounds like something may be wrong with this engine. Bad baffling
could be it if it is running very hot. Nothing you do with the mixture
should make that much difference in oil temperature. If your prop (fixed I
assume) conforms to the type certificate, over speed should not be a problem
unless you descend without pulling power.

It was the use of carb heat during leaning that raised the oil temp...

That engine should run fine WOT for hours. If you are pulling power after
five minutes on a 10 - 20 minute climb, you are making the engine work
harder and get hotter.

We haven't flown it very high yet...

Fix your baffle problems immediately. Make sure you don't have any
induction leaks and the engine is set up properly.

Yep...

If you are not a member of the Cessna Pilots Association, join. The $40.00
dues has saved us literally thousands. Read Deakin's articles on engine
management at Avweb.com. They are mostly about larger and more complicated
engines but you'll learn some good stuff about yours. Search the CPA fourms
for threads on leaning and engine operation.

Yep...