Steve -

More information is needed. What engine do you have?  Engine or remote
mounted oil cooler?

Have you had your engine instrumentation checked for accuracy? This is the
FIRST you should take.

Is the oil temperature sender mounted in the correct place?

As a trouble shooting method you might try installing temporary probes on
the inlet and outlet sides of the oil cooler and determine the temperature
differential.

As an aside I know of a guy with a Piper Dakota (O-540 Lycoming I believe)
that had chronic high oil temp problems after a factory overhaul. A lot of
things were tried and I believe that in the end Lycoming replaced the
engine.

Good luck,

Ted Stanley - A&P-IA