From: David Harlow, email@example.com
Subject: RE: New Mooney Owners Poll
I would suggest an additional option to your survey: For those who do oil
analysis, have you ever had an engine problem that went undetected in oil
analysis results? I recently had an engine teardown to repair a cracked
case, and a badly worn camshaft was discovered in the process. Oil
analyses up to that point time had been declared normal.
Subject: Re: New Mooney Owners Poll
I also had a similar experience, oil analysis every 25 hrs, normal wear
indicated, next 25 hr oil change, oil screen looked like a silver mine.
Several piston pin plugs were badly worn, one even sideways, cam shaft also
Subject: New Mooney Owners Poll
I realize that we don't have a slot for these occurrences. Please just post
a message to me regarding "oil analysis: yes; engine problems anyway." I'll
group the comments in a summary at week's end -- or you can continue the
I've talked with mechanics who swear that when the sample is taken will make
all of the difference in the work to test results (at the beginning, middle
or end of draining). They note that metal particulate and dirt are far more
likely to emerge from the last oil in the crankcase.
We too have lost an IO-360 despite oil analysis. However, in our case I
can't point a finger at the oil analysis because the engine's demise was due
to detonation, which can occur quite rapidly.
In any case, thanks for your comments.
Subject: Oil analysis
I have not done oil analyses on my present Mooney which I have owned for
7 years. The previous owners did regular oil analyses which always showed
normal results despite a broken ring. The only indication of trouble was
that the oil consumption doubled. I have a different engine than the
From: Larry Fenster, firstname.lastname@example.org
Subject: RE: Owners Poll: Oil Analysis
I have had several experiences where oil analysis warned me of a problem.
Once, on my F, the Ram air door seal wasn't sealing, and the silicon (dirt)
levels climbed. We went looking for the cause (I hadn't been flying in a
farmer's field etc.), and found the seal problem - fixed it and the silicon
dropped. More recently in my K, the metals were climbing indicating wear in
the cylinders, and after 3 oil changes we decided that the engine needed a
top (channel chrome - another issue). But in both cases, the oil analysis
trend indicated that a problem existed.
I also had an accessory gear shed a tooth in my 231. The metal was evident
in the oil filter, but didn't show up in the oil analysis. We believe that
since the metal was in large non-suspended chunks it didn't show up in the
oil analysis - but it certainly wasn't hard to see in the filter.
In conclusion, I like the belt & suspenders approach - do both. I think each
will catch/miss certain types of problems. Clearly you would be foolish not
to open the filter, and in the overall "cost of flying", the oil analysis is
to cheap not to do. As an example, in the case of my F, if I didn't have the
oil analysis, I would have kept flying without fixing the ram air seal, and
the silicon / (grinding compound) would have kept grinding away inside the
engine - far more costly than an oil analysis.
Larry Fenster 231 Denver
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