Oil leak copilot side
 

After every flight an oil stain appears on the copilot side behind the cowl flap opening.
I think it maybe coming from the breather tube but i am not sure.
I am preflighting with 7 quarts of oil on the rear eng.
is there a way to prevent this mess?

https://ibb.co/rydb2p3

There is a school of thought that says this stops on one condition.when you run out of oil.

That being said. I have found that the oil dip stick is useful but is relative to your plane. If the plane always is covered with oil at seven, run for an hour and see if the level is maintained. There are quite a few folks on this message board that run at 6 quarts... I have found that at 6.5 it is stable.

Thanks Frank ill give that a try.

I also saw airwolf makes a air/oil separator for the 337 does anyone have any experience with this kit?

http://www.airwolf.com/aw/applicatio...W330_Rev_X.pdf

https://www.aircraftspruce.com/catal...s/08-13591.php

Oil Leak
 

From what it looks like, The gray coloring might indicate something else. It almost looks like the gray oilish residue one gets when there is relative motion between cowling connections. That said, it usually doesn't travel that far by itself. May there something else leaking in the engine that would help migrate it that far up. Just spitballing here. Kind of an unusual oil leak.

Looks like oil is coming out at the bottom of the cowl, then being forced upward by the slipstream. There could be many things leaking, but that's in the area of the valve cover gaskets. Simple to tighten them up with a flathead - There's usually one or two that surprise me how loose they are. Another thing in that area that commonly leaks are the pushrod tube o-rings that are held against the engine case by spring tension. Clean the engine with some 100LL out of a pump-up spray bottle, wash it off with water, let it dry, then go for a short flight. The source of your leak should become clear. My Bonanza leaked oil from its accessory case - it was not something you fixed, it was something you accepted.

Air wolf was an easy install and worked great. May take a half a day and a little bit of drilling but we’ll worth it.

Just follow the directions. And send in the Form 337 on the engine.

On another note. Oil on the rear cowling might be from the front engine too. Usual culprit are the engine drain plugs located on the accessory section.

Enjoy.

M20 Air/Oil Separator
 

They put the M20 air/oil separator on both engines (STC SA02033AT) on my G model. Apparently work great!

http://m20turbos.hypermart.net/breather.htm

My rear engine leaks oil and leaves a mess just like in your picture. The discoloration (grey) is from the engine cowling rubbing together. Let it get wet enough with oil, and it will be more black over time..........know this from experience. I have looked all over the place on my engine and it is in the shop now getting the push rod tubes resealed as well as the oil cooler gasket replaced. My engine is totally dry on top, with oil dripping from the push rod tubes. Plane sat for a while and the seals dried up. Mechanic showed me one and it literally has cracks on it. Zoom in on the attached picture.....same oil issue.

Since my plane is solid orange, it is not as noticeable, but still embarrassing.....Leaves a puddle of oil like my VW Beetle does, but I don't want to use the same saying "the only time is stops leaking is when its out of oil".