D13 engine oil sample came with copper 66

That's what mine was, oil cooler leeching copper.

 

Agree. One has to compare things across the entire oil sample. One item could be just a fluke. And when it is only one item, then doing another sample later should tell. This is why it is critical to do regular oil sampling and tracking trends and patterns in oil samples and watching how various things change over time. Something like bearings, air compressors, etc going bad will give many clues long before it has reached critical. A sudden spike in one area could be something as simple as a change in the oil formulation. Motor oil makers change variations on their blends from time to time, and sometimes a change can cause a one time spike in a particular wear metal that settles down later.