High oil temperature on 912 iS

Check things like an oil hose with too sharp a bend that causes a reduced radius and slows oil flow. Check the air flow opening to the oil cooler. What is your max rpm in level flight? Anything under 5500 WOT is over pitched and causes higher temps. Plus don't fly in the 4K rpms. Stay up into the 5K rpms in cruise.

Can you please explain why you consider it better to cruise above 5000 rpm?

Vlad

Peak torque is at 5252, as you drop below that you are on the low side of your power curve.  You are overloading the engine.  100% power is 5800, max continuous is 5500.  Peak torque 5200, 5000 is a nice 75% power.  75% to max continuous is the best range for cruise running.  65% power is 4800 and anything below that is just silly, the engine was not designed to run continuous below 65 to 75% power.  

Cheers

What RW said.

Most pilots cruise around 5100 - 5300, but your prop pitch can not be over pitched which means WOT at your average altitude needs to be over 5500. You do not want to over stress the engine or sooner or later it will get costly.