Going out for my second sortie and while in the climb with full power I got that hot oil smell and a bit of mist in the cabin.  Closed the heat control valve, reduced power and "bee-lined" to the airfield with good oil pressure while venting the cabin. Taxied in with good oil pressure to a shutdown in front of my hangar.

What a mess...I was down to just below the min line on the dipstick.  Luckily I have another oil cooler (AERO-Classics) on the shelf which I've been meaning to put on since this summer.  I've heard bits and pieces regarding the quality of the UL provided oil cooler and wanted to see if a different cooler might help out with cooling (and quality?)  Anyway, something to think about I guess...

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Glad you got it down quickly David. I will be paying close attention to my oil cooler like everyone else. Thanks as always for keeping us in the loop on your progress and difficulties. You are proving to be the point guy on all things UL, the good and the bad.

No external oil cooler would be much better.

Jan, I hadn't considered that! I bet I could do without the external oil cooler during the winter months.  Probably not during the summer though.  It's kinda of beyond my brain bandwidth to consider cowling design which might enable me to go without an oil cooler thru summer.  Any thoughts?  Cheers!   Dave...

Yes, I blew two off the supplied ULP oil coolers in first 80 hour on my 750. See attached photos of my installed Aero Classics. I made brackets, and installed four  rubber mounts. Also had to widen and lower o/,c nose. 320 hours. now. 



  Your mounting approach differs from what I visualized. Any chance of more photos of your finished install? They don’t have to be perfect, just good enough to provide idea of how you attached to block, bends, etc. Any insights on how to modify cowling would be appreciated. I was not planning on using rubber mounts, your thoughts and using them would be appreciated.

  Like David’s plane, mine is sitting in hanger with parts strewn around awaiting assembly. With 260 hours on clock I am becoming uneasy with flying without install of new cooler.

  Feel free to call.


Ph 208 785-2561


Ron, looking at the second pic with the trim work on the cowling.  I trimmed quite a bit today and am very close to getting it finalized after 4 or 5 iterations.  What do you mean in the statement above "widen and lower o/c nose"?

Thanks!  Dave


At the oil cooler the fittings were  rubbing on the cowling. I cut the nose out and lower and widen it one inch. Then fiberglass it back.Similar to the OneX, were I fabricated a nose and fiberglass it to the Sonex cowling. 

Subject: ULP oil cooler replacement with Aero-classics on 750.

Attached photos:



Great pics, tomorrow I will have access to break, can hardly wait to use your ideas!


Do you know the Part/Model number for your Aero Classic Oil Cooler? Looks like it is a 10 row. But there are two listed.  Should I get anything else at the same time?  Thanks, Greg

Greg...I have the 10 row (8000081 non PMA) which I purchased from Ray Lawrence (UL Power rep).  It is listed with Aircraft Spruce also.  Aircraft Speciality makes some pretty nice high quality hoses for the oil cooler and 750 setup http://www.aircraftspecialty.com/zenith701750.html

Hope this helps and good luck with your project.



Perfect timing on your response! I was just getting ready to crawl under my engine and attempt to read the faint numbers on my oil cooler when I saw your response!





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