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Hi Douglas, what's the ambient temperature, and how are your CHT's? My oil gets up to about 210 on a 90 degree day. Also, have you verified your oil temp sensor accuracy? My MGL setup was 30F off before I calibrated it.
The simplist and most obvious would be to check for baffle leaks or air bypassing cylinder fins.
Mine ran 225-235 on my first flights, that was with a fresh overhauled Continental not broken in and I'd have to back off to keep temps from climbing. After a few tweaks on intake inlet size and exit cowl size, adding a lip at the exit cowl, and completing the break in process, I've got mine stabilized in the 190-205 range on summer days here in Texas where you are. As Clint asked, what are your CHT's? Ultimately, that will be the key to dropping your oil temps.
Also forgot to ask, are you making your first flights with a fresh overhauled engine?
Here is some additional info you might consider, by adding these under engine baffles and cutting some holes in my cowl I lowered my oil temp by 8-10F. This was after I spent some time getting my CHT's optimized.
Hi Douglas, Do you have any pictures of your cowl outlet? I had to make a rather large change to get my CHT's down on warmer days, thankfully most of my test flight period was done during the colder months, so I had a good safety margin while figuring things out. It seems most folks have found that the cowl outlet size and geometry is very important for allowing hot air to escape. But send some pictures of your inlet, outlet, and baffles if you can, it might help spur some other ideas. My exhaust is quite different than the zenith setup, but the zenith setup has worked for others it will work for you too, might take some experimenting.
Speaking of changes to the cowl outlet size, I am including a photo of how much I changed mine and how I added a lip to it. That change, along with increasing the cowl intake sizes by about 3/4” in height, helped to get my cht’s and oil temps down to good numbers even on hot summer days. The minimum ratio of inlet to outlet sq. inches is 1 to 1.5, and that is the minimum. The outlet can be larger and it only helps.
i'm running with an oil cooler, no problems with oil temps, only mod is a lip on the cowl outlet