wrote:

Definitely have an A&P borescope that engine. Broken ring maybe.

Talked to my mechanic this morning. He said not to worry; the dirty oil is
from the oil cooler and its plumbing, which don't get drained when the oil is
changed.

He said I would have noticed this before if I had ever checked it two hours
after a change. Since I check the oil before every flight, it seems I would
have noticed the oil's turning black this soon before.

Should I pay to have the cylinders 'scoped?

--
Dan
C-172RG at BFM