Oil temps - 200 okay?

[kevinh]

Hi ya'll,

So I'm still tweaking my baffles and I have a question:

I had been flying (happily) with oil temps of 180F and peak CHT at 398ish in cruise. But there was a bit of span between the CHT temps, with #2 being the coolest. I wanted to get the CHTs more equal so I could lean more agressively (at lower altitudes I had to run richer than I would like to keep the max CHT below 400).

I recently tried slightly increasing the height of the ramp in front of cyl 2 (by using aluminum heater duct tape - highly recommended for quickly trying these sorts of changes). With this change the CHTs are pretty equal, but the oil temp is a bit higher: At cruise the oil temp is to 185 ish, but climbs or loops will have it at 195.

So - any advice? Would you say that hitting 195 OT in a climb is a fair trade off for CHTs being more equal by about 30 degrees F?

This is all with an O-360-A1A, one lightspeed, one mag and a carb. I'm using Aeroshell 15W50 oil.

[mahlon_r]

Oil temp at 195 is cool by me...no pun intended.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at you own risk."

[Kyle Boatright]

Back during the early days of flying my -6, I had oil cooling issues (I saw 210 fairly often, and 220 in extended climbs). I spoke with Exxon, Aeroshell, etc. and they were not concerned about those temperatures. In their opinion, the ideal range is 190-200F...

[kevinh]

Good feedback - thanks guys.

[Mark Burns]

Kevin,

To add a data point, what oil cooler do you have.

Thanks,

[Tom McCutcheon]

I've recently been told by experts that 180 to 210 is ideal for oil tem. And, that up to 240 is OK but that anything over 240 is red line. I'm planning on making a green line from 180 to 210, yellow from 210 to 239 and red at 240.

[pierre smith]

Mornin' everybody..........(yaaaawwwn),
I was once told by a racer that the engine makes the absolute most power as you cross the finish line, in first place, with all the temps maxed out just before it blows up!

Seriously though, high temps make the engine more efficient from a BTU (British thermal underwear??) standpoint. Auto manufacturers are using thermostats over 200 deg for the water and oftentimes your oil may well be 220 or so but we just have a silly gage with a yellow and green arc. Our 6A has been running around 190-200 in cruise and close to 215 climbing but that's OK. We have a firewall mounted 7 row cooler but only a 2" duct running to it from the left rear baffle and figured that might have to go to 3" but so far, so good, even at 90 ambient.

[Walter Atkinson]

Pierre:

**Seriously though, high temps make the engine more efficient from a BTU (British thermal underwear??) standpoint.**

Not true. A hotter cylinder will make less HP than a cooler one. The volumetric efficiency is lower in a hotter cylinder.

Walter

[pierre smith]

Live and learn....thanks

[Mel]

But the oil does work better at higher temps (up to a point of course). Mine runs around 190-200 in cruise, 210-215 in climb.