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Milky oil coming out breather tube


Well-Known Member
Supporting Member
Sep 14, 2022
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Duluth, Minnesota
I have a C90-16F. Installed on Cub 1974, looks like a complete overhaul in 1981. 707 hours since. I’m a new owner, I fly cub on floats. The dip stick has 2 marks on it, the sump is longer neck. I originally serviced to top line but started thinking it was to much( also a marker much higher on other side. I’m not sure how much oil is in it, probably the only way to know is drain oil. The belly gets oil and some spray marks on left side of windshield. I’ve read a lot about finding the sweet spot for oil level. I also know some top end problems, blow by etc can cause this. Compression was good in June, last annual, all 4 cylinders 72 or 73/80. I got the plane in July and has had the problem. Oil level has been going down but not much, hanging around the 1st mark(lower of the 2) obviously I don’t want to run low on oil, but also trying to see if less out the breather tube. Or do I bring it back to guy who did annual? Thanks for any advice.

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