I have a 2004 (engine year) C13.
When I bought my Coach in 2017, I had an engine oil analysis done. Everything was fine except the copper was a little high at 96 ppm. The analysis notes said not to worry. I changed the oil then. It's 40 quarts of Rotella T6 15W-40, and a new Cat filter.
In Sept 2019 I sent out my next sample. This time the copper came in at 65 ppm. The "universal average" is 24 ppm.
At least it was dropping, but still over the average. I changed the oil again after sending out that sample.
Now it's 2021. I sent in my latest oil sample a couple of weeks ago (Nov 2021) and the copper came back at 318 ppm. Everything else is in the normal range. I plan to change the oil again this weekend. Rotella T6 15W-40.
So what should I do?
The only source I can think of for this copper is the engine oil cooler. Nothing else in the engine is copper (if the crank/rod bearings were worn I'd have other metals showing high).
The oil cooler runs around $1300 - but worse, it's real hard to get to (I'm not even sure it can be replaced with the engine in the coach, as tight as the engine is in this frame area). Should I plan on replacing it?
Does anyone have any other thoughts on this?
Perhaps wait another year (another 5,000 miles or so) then retest the oil.