Follow up
I've read lots and lots of threads and there are times when a thread contains the same issue I'm dealing with. I read and read only to find there was no conclusion to the saga, or none posted. So since I started this thread and another similar one, I will give the conclusion to the saga in the hopes that it will help someone....someday.
To backtrack. My original issue is this. Engine is an IO-360, Superior, 750 hours, regular use. It was oil fouling the bottom plug of #4 cylinder. Not huge amounts but more than the other bottom plugs. I did a mag check one day and the plug wasn't firing. I pulled it and it was oil fouled. Then my most recent oil analysis report came back and it showed 12 times higher Chromium (normally 5 ppm and it was something like 70 ppm) and elevated Iron (normally 25 ppm and it was 62 ppm).
I freaked out and started reading and posting questions. The plane ran fine, compression was fine, started fine, no metal in the filter, no excessive oil burn (burns about a quart in 30 hours).
I came back from my San Fran trip and pulled another oil sample. Still elevated Chromium and Iron after 16 hours.
I decided to pull jug #4. Not a simple task !!! The baffles have to come off, a bunch of stuff to disconnect and special wrenches required to pull the base nuts at the bottom of the jug. Much easier said than done !! Also, we had to get the piston off by pushing the piston plug out. EASIER SAID THAN DONE. I'll spare you the gory details of how we did this, but suffice to say we damaged the piston and the copper bushing on the connecting rod. Those had to be replaced.
I was looking for a broken ring, scored cylinder something. Nothing was obvious. There was some wear at the top of the jug where the top compression ring stops and changes direction, and a little wear from the piston skirt touching (perhaps from a cold start). But no smoking gun.
I was disappointed and glad at the same time. They honed the cylinder, put new rings, new piston, new bushing on the connecting rod, checked the valves and gave it back to me.
I hired and AME to help me put the jug back on. I wrecked enough stuff taking it off and didn't want anything to go wrong with the re-install. He brought by his fancy tools and his digital torque wrench and helped me. Then i spent the next two days putting the baffles back together and cleaning up stuff under the cowl.
So....... was it worth it?? NO!!! or at least I don't think so. I did learn how to take a jug off and put it back on, I did see the guts of my engine, learn how to use some new tools. I got to see what my finger looks like with safety wire run right through it !! and how to make a bandaid out of blue shop cloth and masking tape
Here's what I should have done. Not panic first of all. With elevated numbers in the oil analysis, watch the trend. The trend can only be developed with more time and oil samples. With good compression (all cylinders were 76/80 and above), no metal in the oil filter, no excessive oil burn.......leave it and fly the darn thing.
Sample every 25 hours if need be. Oil is cheap compared to what I did. If the numbers rise and then stay the same for several hundred more hours.....so be it. As long as the compression is good, no metal in the filter etc.... just go fly.
These are parts per million we are talking about, don't freak out.
If however the trend is that a particular wear metal goes from 5 ppm to 70 ppm to 250 ppm to 600 ppm in subsequent 25 hour oil changes, well then you need to start checking into what the cause is.
Finally, possible causes. From what I can gather. The rings are suppose to turn through out their life. Sometimes they can align. This could cause oil to escape and foul a plug, this could also cause some extra wear if they get stuck. The solution, you guessed it, keep flying, observe and see if the problem resolves itself.
I have only flown 3 hours since the new jug was put on. I was told to run regular oil and fly WOT for 5 hours. I take off and keep the power at 80%. I burn more gas but it's fun flying fast
Hope this helps someone someday.
Darren