"Dan Luke" wrote in message
...

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

My 0-320 powered RV has an oil cooler with the associated plumbing. The oil
still looks like honey 20 and more hours after a change. It has never been
dark after only a few hours.

You could perform a simple compression check. Turn the mags off, chock the
airplane, and pull the top plug from each cylinder. With someone else slowly
rotating the prop, do a thumb test over the plug hole for compression on all
4 cylinders. You should be able to notice if one cylinder is considerably
worse than the others.

As always, treat the engine/prop as if the engine is going to start abruptly
anytime you're moving the prop.

KB