All this discussion of chain stretching confuses me. If the links on the sides don't actually get longer, I fail to see how the chain gets longer. If the rollers and pins wear the space between them changes, but this is not cumulative. The center of each pin stays in the same relative location that it was when the chain was new. And how does oil changing affect the stretching of the links?

If the chain fit the to sprocket gets sloppy, and the sprocket is wearing and getting smaller in diameter where the chain engages the teeth, then I think I can understand how the chain would seem to have gained and "apparent" length. Otherwise I am not able to see how the chain gets longer. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)