I guess I just have to try a lower OCI and the Wix test kits to see if it goes away. What annoys me is I may never find out what it was. Was it an incorrectly done test? Was it some kind of contamination? Was it actual damage? Was it caused by the oil? The filter? If it was the oil I won't know until at least the next oil change. Maybe my driving style? I tend to drive long highway miles at high gear, low RPM, maybe 70-75mph with RPMs down at 1500 for long stretches. I'm very gentle on the throttle and try to drive as if I don't have brakes (if I see a red light up ahead, I'll coast rather than speed like a maniac and jams the brakes at the light).
I guess in the grand scheme of things ~27ppm is tiny, but still alarms me if it's wearing. Especially because I've done about six or so UOA's and this is the first time anything like this has popped up.
I checked the air filter yesterday, with a flashlight and everything. Air filter is still clean, barely dirty, no holes, seals fine. It's OEM and fits perfectly too. No dust on the inboard side of the air cleaner housing either.
I'm stumped.