Mike, I wonder if the rings just got majorly gummed up and are not allowed to clean the walls as their are supposed to. The records I got with the car show a history of pretty regular oil changes at 3k. I wonder if the machine shop that did the heads is as good as my mb mechanic wants to think. First vjob, began using 3 quarts in 800 miles. Redone and everything tightened up and it went back to where it was b4 the first vjob. This machine shop is a different shop from where the dealer uses. I have wondered about the shop myself. Oh, well, we will keep trying until maybe one day we figure this thing out.