Just finished my annual inspection with 400 hrs on the 350iS. With minor exceptions the engine has been awesome so far. Compression's are all high 70's, oil usage is less than 1/2 qt in 50 hours. Every couple years one of the valves needs a minor tweak. No leaks, starts great. No complaints!

Just curious...what kind of oil temps are other 350iS users seeing. I typically run between 186 and 210. The 210 is rare on only after a climb in the dead of summer. I'd say my average is about 190. Those are all F readings.

Looking forward to seeing what others report. Thanks in advance!

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With stock oil cooler on a hot (90 degree) day my oil temp would climb past 215 and make like 220 was fast approaching. On cooler days the temps were fine. I expect to install a larger after market oil cooler in the next couple of weeks.  My engine is a 350i.


Thanks for that info.

David, glad to hear you are happy with the engine at 400 hours.  Bodes well for the rest of us UL owners.  Up here in central Maine I'm experiencing a range of oil temps due to a couple variables.  Changed out factory cooler for an Aero-Classic cooler which helped notably when flying this summer with floats and OAT close to 90F.  Dropped oil temps back down to 190-200 range from the 200-215 range.  Now back on wheels/skis for late Fall and Winter I have blocked off approx 2/3 of my oil cooler to keep oil hot and am running 185 - 200F on 30F OAT degree days, near max gross of 1440 # and 2600 RPM.  As Winter cools things down even more, I should be able to maintain at least 180-185F on oil temps.  I worked last Winter, but that was with the factory cooler.  The Aero-Classic is more effective as a cooler and may have to adjust or block off even more of the cooler.  If you don't mind, what year production is your engine?  Mine is a Nov 2011 manufacture and there has been a few "teething" pains, which hopefully I've worked out by now with 140 hrs on the engine.


Thanks for that info. As to year of mfg I think it was late 2012 or early 2013. We installed the engine in March 2013.

I had all kinds of high oil temperature issues using an "after market high performance" oil cooler on my Rotax 912 in the CH601HD. Instantly 3 months of grief was gone with the installation of an Aero Classic aircraft engine oil cooler. Just my 2 cents.


Flying with UL 350i in our 650. Summer day with 90+ temps, oil temps are 185 - 190. On hard climb out can get me to 210. Obviously, winter days here in Nebraska are not a problem. Using Dynon monitor for these numbers.

Still using UL supplied oil cooler. Have the Aero classic style cooler in a box on the workbench. Have not taken initiative to try to install. Cooling not a concern for me, but still thinking of reports of failed oil coolers in flight. I have 370 hours.

Either my cooler is good and it is never going to be a problem or else it fails the next flight.

My attempt at " Gallows " humor.

Thanks for the input. I'm also using the original oil cooler mounted at the front of the cowl. No problems with it after 400 hours. I did change out the lines with teflon lines a few years ago.Your temps are very close to what I see as well. 


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