Oil Analysis

If you could only do one thing: either lab analysis of oil after each
change, or your own visual examination of oil and filter after each
change, which would you do?

I'd quit, on the basis that the universe had just become too perverse in
contriving such a situation.

Visual inspection will catch some problems, oil analysis will catch
others. The two sets of problems have some things in common, but a lot of
things will only appear in one or the other set.

Bob..

......my experience has been with large marine engines, and I
always sample and get an analysis done at each oil change...and if I
owned an aircraft (and may soon) I would also do it ....

IMHO... the analysis will pick up problems long before you
(or your mechanic) will visually see the particles in the oil
filters.

...and yes, I have cut apart a good many of them ... (filters
that is)

And talking to whom I believe are PROFESSIONAL mechanics,
they tend to use ALL the diagnostic tools available to them.. and
they consider oil analysis a cheap and useful tool.

I know of a couple of engines that had bearings replaced
when the copper content went up suddenly (before a bearing spun and
did major damage)

Now, one sample is not very helpful... but several taken
over time establishes the "normals" per period of operating
time... it is the sudden deviation from these "normals" that trigger
the further investigation..

Cheers!

Dave


On 08 Nov 2003 17:20:10 -0800, Bob Fry wrote:

"Don Gourlay" writes:

We used Blackstone for a couple of years. They alerted us to the fact that
the aluminum content had shot up. Ended up doing a top overhaul. Previously
the leak down tests were ok. We had heard this can change quicky which it
did. The analyiss was the trigger. AME said things would be been fine for
about another 100 hours but we did the top anyway.

A lot of people on the field laughed at doing the analysis every oil change.

Don--

I have an Aircoupe with a C-90 engine. First airplane owned so I'm
still learning. OK, my mechanic is skeptical of lab analyses, and
prefers examining the oil and filter after each change. Best would be
to do both, but my question to you and others is--

If you could only do one thing: either lab analysis of oil after each
change, or your own visual examination of oil and filter after each
change, which would you do?

In your above scenario where the lab alerted you to a problem, would
you have noticed the problem by doing a visual inspection of oil and
filter--like seeing metal particles?