Sounds like some serious blow-by into the crankcase. If you don't have an
oil separator on the breather, I would expect also to see a very dirty
belly. How about having a mechanic re-check the compression and look at
the inside of the cylinders?

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Best Regards,
Mike

http://photoshow.comcast.net/mikenoel

I'm a uniter, not a divider. - GWB, 1999.

"Dan Luke" wrote in message
...
The oil in my Lyc. O-360 F1A6 is black only two hours after being changed.

What could be causing this? Compressions were in the 70s at annual in
September.

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Dan
C172RG at BFM