I can agree with the statements that oils and engines are built better now, so you can go longer than the old idea of 3,000 mile intervals. The question though would be when did it change.. I mean just because oils are better now, does that mean an engine that was designed around 3-5k intervals can now magicaly go the 10-15K interval. Yes "new" cars run much cleaner so the longer intervals can be done, but what about those of us driving cars that much older than what is considered "new". I doubt very much that with my diesel at nearly 228K miles can just suddenly change to 10K mile oil changes just because the oils are "better". I don't mind going 5-7K oil changes in my VW Passat because I have had since it was new, VW recommends 5K intervals of reg. oil, and I have been using synthetic oil (Valvoline Synpower 5W-40) since 10K. So basicly, what is the driving factor in the intervals, the quality of the oil or what the engine was designed for.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section