I didn't have time to read all 12 pages of this thread but I have 5W-30 Mobil 1 in my Duratec. I had the oil tested by the lab at around 6500 miles since the change. They said my upper cylinder metals were above average. When I tried 5700 miles for the next change they said the numbers came down and the Mobil 1 formulation had changed from the first oil sample but I was still above average. They recommended 5300 between changes. They said the average change interval for the 2.5L was 5400 miles so they didn't think the oil was at fault.
Is Mobil 1 monkeying around with the formula so they can compete on price with Syntec?
