At OCIs over 13k, the PUP was still in grade and had plenty of reserve TBN. At the 17.1k sample, there was some slight oxidative thickening but TBN was still OK and insolubles were 0.2 IIRC… talking with HPL he said this is normal, and would personally determine condemnation of the service interval when the oil crosses into the next higher grade if TBN and flash point were acceptable, so if I had kept the car I probably would have pulled back to a 15k OCI.
Obviously trends tell the rest of the story of how the oil is doing, and even on the 17k run, iron wear was only 1.1ppm/1k mi. I’m not saying every engine can run 15k on PUP, but I am saying I’m at least as correct as the people who’ve never used PUP yet claim the oil is not capable of extended UOAs, since I ran 8 or 9 different UOAs of increasing distances on it to generate data and come to my conclusions.