You can’t infer actual wear from a UOA ...
Yes- you can. I'm going to nit-pick here in your choice of words.
UOAs do not show all wear; that is true, because they cannot see wear particles larger than 5um. But the UOA will show a very accurate level of small wear metal particles, and than can, in turn, imply the loading of larger particles, because
multiple SAE filter studies have shown a very good correlation between the overall particle loading and the UOA results. If there is a good wear signature in the UOA, (directly showing low ppm counts in small particle sizes), then the PCs echo this in the lack of heavy particle loading in larger sizes. This effect has been confirmed in more than one SAE filter study. UOAs can tell you composition, but not size. PCs tell you size, but not composition. But together, they can compliment each other with implied logic. My point is that you can we cannot infer "actual wear" from a UOA; that's just not true. We can take the inference from the level ppm of seen particles, which in turn implies the level of loading in larger particles.
Further, UOAs have also shown good correlation to other means of measuring wear, such as electron bombardment weight analysis. Same generall effects are present; low ppm in a spectral analysis is echo'd in the calculated mass change of EB measurements, as also seen in SAE studies.
So, yes, UOAs are a good representation of the overall wear. They are not perfect, but they are a very cost effective means to get a good idea of wear.
This UOA shows good wear, low contamination, and strong TBN retention.
If the QS UOA comes back good also, I'd say 10k miles is a no brainer OCI.
