We switched from Aeroshell Multigrade 15w50 to the Exxon Elite 20w50 in
a Cherokee Six with a Lycoming 0-540-E4B5. We had decrease in metals as
well. Decided to just stay with the Exxon. This was by no means a
scientific study. We had 4 analsis before the change and are now up to 4
after. These were 40-50 hour changes in southwest Virginia in various
seasons. The plane if flown roughly every 2 weeks year round.
Peter R. wrote:
With my rebuilt Bonanza engine, I have been faithfully sending in every oil
sample drawn from the 40-50 hour oil change to Aviation Laboratories for an
oil sample.

When I receive the report from the lab, I log it to an MS Excel spreadsheet
in order to catch any trends. Currently I have seven oil analyses logged
over the 300 hours that this engine has on it.

Normally I use Aeroshell Multigrade 15w50, but last winter I used Exxon
Elite 20w50 for one of the oil changes under the assumption that it would
combat corrosion that might occur from condensation build-up in the oil
after engine-shutdown.

An interesting data point has emerged that has me curious. All of the
metals discovered in the oil analysis after using Exxon Elite were of
significantly lower quantities when compared to the analyses from the
Aeroshell multigrade, either before or after the use of the Exxon Elite.

Is this just coincidence or does this indicate that perhaps Exxon Elite
does provide better engine lubrication?

My aircraft is a few hours away from an oil change and, as we approach
winter in the Northeast, I am considering using Exxon Elite again.