Low oil temperature on 915iS.


Super Member
Mar 17, 2013
Ponce Inlet, Florida
Total Flight Time
700 hours
While on the subject of gas, we are very lucky to have Swift fuel 94 Octane Avgas at Deland Airport. Oil stays clean twice as long as ethanol free Mogas and 4 times as long as 100LL. 100 hours between oil changes is no problem. No exhaust residue on the props either. If you can encourage your FBO to get Swift fuel if you run Rotax's


Gold Supporter
Oct 24, 2012
Québec Canada
Dominator installation of a Yamaha Sidewinder Turbo , Big tires and FOX 2.0 AIR shocks
Total Flight Time
student pilot at the moment
Preventing (to the degree) an oil coking is very easy: use fully synthetic oil (Mobil 1 Racing 4T). That would require the use of unleaded gas, of course. Aeroshell Plus 4 - is semi-synthetic and thus more prone to oil coking. Been there...

Also for the idle cool down time.. , some interesting info

the rotax 914 turbo is a small garrett t25 with journal bearing oil cooled

for the 915 it is interesting - rotax change from garrett to precision turbo a smaller aftermarket

company popular in drag racing , they normally dont have compressor map to see

the precision turbo for the 915 is ball bearing oil cooled only

garrett ball bearing is liquid cooled also they have a paper on why on this subject

How does water-cooling extend turbo life?​

Robert Young is the engineer owner and founder of Forced Performance

he work on turbo for many year , he create is own high quality brand Xonarotor turbocharger

and create is dual seal and billet wheel before the OEM


he explain in this video the difference in cooling needed with journal bearing high flow oil cooled only

vs ball bearing with no water cool with there restricted inlet low oil flow to the centersection ball bearing cartrige , hydro damping cartrige and oil cooked , hydroplaning ball with to much oil flow and rpm effect

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Gold Supporter
Dec 15, 2020
ELA07S and Montgomerie Bensen (project)
Total Flight Time
Products of gasoline combustion are mostly water vapor and CO2. Some of it goes to crankcase, and condense on oil if oil temperature is below water boiling temperature at the flight altitude.
If temp of the oil were over 100C - water vapors would not condense on the oil and would not become a part of lubrication stream. That is my opinion and I don't insist it is correct, but as I said, it is easy for me to replace the thermostat and forget about that problem, be it real or imaginary. :)
Hi Inquiring Mind,
How is the Improved Racing oil thermostat system working out for you on your Magni?
I have no thermostat valve on my 914 ELA072. Partially covering the oil rad to get 95 degrees C is a pit of a pain.
Many thanks, John H