Changed the oil in the Super Cub yesterday. Since its been so warm lately decided to go with Aeroshell 100W. Oil pressure in cruise is at the bottom of the yellow arc. Outside air temp was 80 degrees, CHTs were 380 and oil temp 180. Pressure came down a little bit during a 1 hour flight. Question: should I change to 15-50 or is there an adjustment? Or just be happy it's not too low ??

There is an adjustment, just depends on what you have installed. Some have washers you can add or remove, other type is an actual adjustment you can turn. It's really not typical to have to adjust oil pressure when changing to a different weight oil, unless it was originally set on the high side and it always ran the multi grade oil and you just never noticed. It also just kind of depends on where you operate, to me 80 degree oat is not a hot day. Central California gets pretty warm in the summer and we regularly see temps over 100 degrees, I normally will go from 15-50 to straight 50 late spring. I will say, before making an adjustment I would actually check to verify the gauge is indicating accurately and then go from there. If you're that close to the yellow removing 1 washer should get you in the green.

Before starting adjustments:

? What was the last thing you did - moved - changed - etc.

What oil were you using?

By Super Cub my assumption goes to at least 150hp - BUT-the first so called Supercub only had 90hp.
Totally different oil systems and possible causes and solutions.

Mine was fixed once by changing out old oil cooler.

My last Lyc 0-300 had couple of things to change and or adj.
Started with ? Vernatherm ? (sp) That is the one that comes in various lengths? definitely various SPRING lengths and colors with plus or minus various amounts of washers based on spring etc. Not a simple as it sounds. The other (gonna WAG it a bit here) is an oil pressure "switch/valve" on upper part of the engine. We found one that had the wrong LENGTH and caused the oil pressure to jump around.

Best I can do for this one.

If the pressure came down a bit after and hour I would do one more flight.
Take off at hottest part of the day - point the nose into the sun - pull the nose up to block the sun from your eyes and do a hard - high power climb - try to get oil up close to 220 - nose over slowly and see if the pressure has dropped back to "normal" That always the effect I got when climbing west out of Windyschmucka every summer. Just an idea - not a proven or approved process.

wannabe wrote:If the pressure came down a bit after and hour I would do one more flight.
Take off at hottest part of the day - point the nose into the sun - pull the nose up to block the sun from your eyes and do a hard - high power climb - try to get oil up close to 220 - nose over slowly and see if the pressure has dropped back to "normal" That always the effect I got when climbing west out of Windyschmucka every summer. Just an idea - not a proven or approved process.

If you do this, watch your CHTs--that's a pretty good recipe for heating them up pretty high.

If all you did was change the oil, I'm a bit surprised that a heavier weight oil would cause that much of a change. I typically run 80 Aeroshell in the winter and 100 Aeroshell in the summer, and although I see somewhat different temps, both oil and CHT depending on OAT, I never see oil pressure higher than normal, no matter what oil I'm running or what the outside temp is. Mine's a 180 hp Lycoming O-360.

Cary

Cary

I fully agree with you. sdfg

I forget that most people here these days don't know how hard my sense of HYPERBOLE runs.

I assumed Scott has the good pilot sense to monitor all temps in the process. My main point was that it may take more than the one hour as I recall. If the pressure still stays "high" after a more of a hotter run, then I would ask for some professional help.