Engine temperatures

If one goes up significantly then yes it will affect the other if they are seperated, but not a lot. If you are going to use the aluminum tape use it on both the radiator and cooler. If both are set back to back then temp changes may be a different from separated ones. Airflow through a cowl over these two items will make a difference too.

On my 912UL installation in my Eurostar, blanking off part of the coolant radiator raises the coolant temperature but also raises the oil temperature. This could be partly due to the reduction of air flow through the coolant radiator, into the cowling and out passing through the oil cooler on the way.

Yes one will raise the other, a hotter engine puts more heat into both systems. Your suggested tape method is a good one it is easily reversable if the outcome is not what you desire.

However all fuel burning engines are basically heat engines so a hotter engine makes less power.

180 F oil temp is fine as is 150 coolant temp, you may only need tape in winter but not in Summer.TL chose a 170 F thermostat for a reason.

The Idea that you need to get to 212 F is a misunderstanding of the physics of heat vs vapour pressure of water. In simple terms at any temperature where water is a liquid some water vapor exists and this will dissapate into the atmosphere thus drying the oil. The higher the temperatre the higher this pressure and therefore the faster this happens. If you had a pot of water at room temperature it would eventualy evaporate and become dry. If you heat the liquid  from say 77F to 180F then the PP goes from 0.0313 to about 0.5 so the "drying" process is 0.5/0.0313 times (16 times) faster. Going to 212 F from 180 F is a litte faster but only twice as fast (1/0.5).

As others have stated so long as you are not getting brown sludge cream under your oil cap then the moisture in the oil is being removed effectively and you do not have a problem.

Rotax does state a minimm oil temp of 50 C and max of 120 C (122-248 F) so 180 F is fine.

Roger.  Thanks for your input!  Quick question.  My Sirius was Flight tested in Czexh republic in the fall of 2016, but by the time it was sent to the US and reassembled and flown it was April of 2017.  Should I be getting my 5 year rubber parts change in 2022 or 2021?  I only have about 150 hours on the plane, especially after 2020.  I read that you are experienced at this.  I have friends in Tucson.  Hard to find ROTAX people that are knowledgable.  Maybe I could fly out there from KJQF.

Tommy

Thanks Kevin and Glen.  I think I will experiment especially with the winter here in NC. 

Tommy