Cautionary Oil Temperature Range

Can anyone give me an idea as to what temperature I should use as an yellow Cautionary Range? I set/input these values for my oil temp display. Right now it is set for 200 and is has been coming on regularly on hot days. I have a Lycoming O390. What temp to establish low end of yellow cautionary range?
Any thoughts?

I see 215 regularly on 60's and 70's days. Didn't think 200 is cautionary unless I'm missing something? o320 on RV6A

I consider 220-240 as Yellow and to me yellow doesn't mean an immediate landing, though I would possibly take steps to keep it under 240. Most oil doesn't start to seriously degrade until 250-260* (oil in the sump is at least 10*s hotter than the oil passing the sensor). High temps lead to faster break down, but we change our oil at low interval times compared to most engines, so this really isn't a factor. Back in the dino oil days, most engine had a 3000 mile interval which is around 100 hours. I believe that Lyc says 235 or 240 as redline, but that was not based upon modern oil stock, which resists thermal breakdown better than it did back in the 60's.
Larry

I will start "doing something" to lower it if I see it hit 230 in a climb. I typically run 190-200 in cruise.

I too would do something around 225-230 range. Although even in the summer (80+ F) I have to keep my oil shutter somewhat closed in cruise to get it above 180. I shoot for 180-190 in cruise. Never seen mine get above 205 but this is an IO-360 not a 390 so I can't speak to the differences.

edstepec said:

I see 215 regularly on 60's and 70's days. Didn't think 200 is cautionary unless I'm missing something? o320 on RV6A

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That seems pretty hot given the relatively low ambient temperatures you quote.

I use 200 degrees for my oil temperature alarm, the hottest I’ve seen so far is about 190 on a 95 degree day.

00Dan said:

That seems pretty hot given the relatively low ambient temperatures you quote.

I use 200 degrees for my oil temperature alarm, the hottest I’ve seen so far is about 190 on a 95 degree day.

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Depends on how the engine is set up. Piston oil squirters add a huge heat load on the oil.