Oil Temp

[Lance]

What are some of the normal oil temp ranges you guys may see in the summer time? It gets really hot here in south Louisiana (90-95) with high humidity. My temp. can get up to 220-230deg. running at 2450-2500rpm.

[roy whitford]

OIL TEMP RUNS 180-190° IN SUMMER. OAT TEMP 65°. IN WINTER I MUST COMPLETELY TAPE OFF THE OIL COOLER TO KEEP TEMPS ABOVE 150°. WHAT KIND OF CYLINDER TEMPS ARE YOU RUNNING?

[Lance]

I have "under the plug" CHT. It spends most of its time around 350 deg. give or take 25 deg. My oil temp is probally in the 190-200 range at 65 deg. OAT.

[CubCouper]

Great time to ask this question! I was up this weekend and watched my temp oil hover around the 230 mark, plus or minus a couple degrees. Of course the plus side had me pretty concerned since that with 10 or so degrees of the red line.

Outside temps here were in the mid-90's.

I normally run Aeroshell 15W-50, but after some conversations with some engine rebuilders, I'm planning on going to straight weight 100W for the rest of the summer.

[CubCouper]

By the way -- my talks with the rebuilders last summer went like this. I was having an issue with losing oil pressure as soon as the engine warmed up -- on cold days it just barely stayed in the green, on a hot day it drift down near 40lbs. We put in extra washers, new springs, etc. to no avail. It was then my mechanic called a couple different rebuild shops for ideas. One suggestion was to go to straight weight oil especially for summer temps. His quote, "15W50 has been the best thing for my business... keeps 'em coming back more often."

This didn't fix the problem either, but the advice stuck. We finally decided to tear things down until we found the problem. Turns out that the previous overhaul had missed a hole in the gasket when he installed the oil pickup tube. The gasket had slid over the pickup passage and blocked it by half.

[Crash]

If your oil temp is running high you might want to inspect your engine baffling seals. Old felt baffel material will compress and let the air pressure inside your top pressure cowl leak over and around the baffling instead of through the cylinders causing excessive heat build up and high oil tempatures. For the cylinders to cool properly the air needs to flow through the cooling fins. The more air flow, the cooler the cylinders will run, and lower oil temps. Put a drop light behind the rear baffling and look throught the nose bowl openings in a dark hanger or at night. If you can see cracks of light around the baffeling seals, then you are loosing air pressure that would otherwise flow through the cylinder cooling fins. I reccommend rubber baffel seals instead of the old felt type. Cut them 3/4" too wide and roll them into the pressure area with the cowls on and closed. This way the more air pressure in the top cowl area, the better they seal. Crash

[cubdrvr]

The owner of a midwest overhaul shop does NOT like multigrade oils. He believes they are the cause of numerous engine problems, especially in the high HP high compression engines. Years ago I used to run multigrades year round.....now I run 15W50 in the winter months only and 100 plus the rest of the year. Seems to be a good combination.

[Lance]

Thanks for the baffeling info crash.

I have the old felt that is in pretty good condition, but you have me curious, is it doing its job 100%. I will check it out.

[Lance]

By the way, I run aeroshell 100W year round.

[PA12driver]

Another tip on the cooling: the front cylinder metal baffle that rests up agianst the cylinders and (is supposed to) conform around the case is usually very sloppy and there is a lot of gaps for the pressure to escape. Suggest that this piece be remade and reshaped? Also a silicone gasket up against the case is a good idea.

The best cooling mode I know of is to move the oil cooler to the rear utilizing one of several STC's. (see photo of my installation on a PA12.

I believe Atlee makes an ajustable baffle for the cooler. Van's of the RV-4 crowd also makes a firewall mount for the cooler that has a lot of merit as it takes it off the (vibration area IE: the engine)

I run max 210F on the oil temp, and the cylinder temp when careful leaning max of 350 (screwed in temp probe on the rt rear cyld.)

(Crash's) advise on the cowl gaskets is a must! Don't be sloppy in the direction they face! always face the silicone flap toward the high pressure, against the air stream to force it to tighten.

As for heat: (suggest you all move to the West coast and vacation in the east we have the low humidity to go with the cool air!)

Have a great summer!

Tim

[kase]

The original oil cooler is not very good. Replace it with a Niagra 20377A all aluminum oil cooler. Same size as original. Direct bolt on replacement. Approved under the type certificate. Engine will run around 20 degrees cooler. Only weighs 3 lbs. Or you can go with the rear baffle mount cooler.