Hi Jim,
"4. Do you have an oil thermostat installed?
5. Are you reaching oil temp of at least 120 degrees centigrade every flight?"
In Q4 are you just asking a question ? or are you suggesting a thermostat should be fitted ?
In Q5 - I stand to be corrected however I am unaware of Rotax recommendation for the crankcase oil to reach 120C or for this to occur during every flight.
I am aware that Rotax (along with many other engine malkers) recommends that the crankcase oil should exceed 100C for a sustained period, at least once in a days flying (not every flight). The purpose of the elevated temperature, is to drive off volatile contaminants eg traces of unburnt fuel, water vapour and byproducts of combustion.