Found this post where the UOA showed no indication of imminent cam follower failure despite obvious visible wear. I suppose it is hard to tell however how much of that wear occured before failure. I have seen lots of these follower pics as they wear and they get very thin before breaking like this one did, so certainly there was quite a bit of wear. Also the end of the fuel pumps (shown) show a lot of wear prior to breaking usually.
Originally Posted By: OOOO-A3
oil change every 5k since new, Castrol Syntec 5w40 VW 502.00. Here's my Blackstone report. This oil sample was from before they did the repair, and I had been driving on it for quite a while so it was not 'sudden' as speculated by the Blackstone tech in the notes. Look at my pictures below.... if a Blackstone report won't pick up evidence of THAT, then it certainly won't pick up anything "before major failure". I had the "B" (good) cam, too: