Oil Still Too Cool Even With Cover

The majority of the oil thermostats only go to 180F. If you want to go over the 200F mark then add some aluminum tape across the cooler and if you already have some then add a tad more to get the temps where you want them. The Rotax 190F - 230F is easy to obtain in cold weather using the tape. Getting to the 212F +/- mark makes sure you cook / boil off contaminates like moisture in the oil. Oil temps in cold weather country is common, but easy issue to deal with.

p.s.

If you live in cold country and have hard starting issues because the engine is too cold then I would install a Tanis engine pre-heater. It will help save the engine and makes starts easy.

Craig, like Rotax Owner and Roger said make sure the temperature reading is accurate and in range first. Also another way to know the oil temperature is too low is if after a flight take the oil cap off and look for moisture, if there is water droplets on the bottom inside of oil cap then the oil temperature is definitely too low. It should be oil only not even milky oil.

I don't even taxi until I see the minimum of 120F, but then, sometimes, it'll drop below that before TO.  On the roll, it goes into the green, above 120F.

In a recent flight, I was seeing a max of around 185F, give or take.

I can't speak to the accuracy of the sensor.

Also, I do have a pre-heater that works super great (http://www.reiffpreheat.com/Rotax912.htm).  Turn that on the night before and the engine starts smoothly and the oil temp is instantly 90F.

I'll have to take more notes on my next flight (and I'll check the oil tank cap after the flight for any moisture).

Use a device like this one and aim it right at the oil temperature probe/sensor and see if it matches the gauge.

https://www.amazon.com/Thermometer-Temperature-58-716%C2%B0F-Backlight-ANNMETER/dp/B08B85T21Q/ref=sr_1_2_sspa?crid=2Q84361N8F7A8&keywords=contact+free+temperature+reader&qid=1675303118&sprefix=contact+free+temperature+reader%2Caps%2C141&sr=8-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExVTRCTFpDT1NQSEpEJmVuY3J5cHRlZElkPUEwNTI0NDU3RDBKMEpWM0RQREpNJmVuY3J5cHRlZEFkSWQ9QTA0NzMyMzIzUDBKMDcwQ1hDQkVZJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

Personal view; I do not like the added complexity & weight of an oil thermostat. Ugh! to all those added connections/failure points.

As many have advised an adhesive foil/tape/even a sheet of aluminium reducing the effective cooling area and or air flow is easy to implement.

For 10 years I flew my last aircraft with a small summer fixed exit air restrictor sheet, which was replaced by a much larger one in winter (In my part of Australia defined as days below 25C). Very effective at keeping operating temperature's at optimum (I like to see oil no higher than 120C in extended max climb out and this must drop to the low 90C's in cruise)