Last night I stopped by the airport and I just happened to read an article
about http://www.oilcoolers.com/ flushing and inspection service. I was
amazed at some of the pictures of the junk that they flushed out of some of
the oilcoolers. I think the cost was about $200 for a multi-process flush,
inspection, and pressure test.

If you pull the mags, check the drive gear bearing that rides in the
receiving boss at the end of the mag shaft. There were several different
designs of the same bearing number. Do NOT use one that has the ball
retainers spot welded or dimpled between the balls. This is an older and
weak design and they will separate, causing a metal making event. Ask me
how I know. The newer and better designed retainers are actually crimped
together over a longer radius. The bearings are cheap, I bought several for
less than $10 each, there is no reason not to replace them every time a mag
is pulled.

Other than what has already been mentioned, borrow a copy of the Maintenance
manual and photo copy the inspection checklists. I'd bet there is one for
500 hours.

Jim