>VW says every 7500 miles, Jiffy Lube says every 3000 miles, and I'm sure
>you can find a few other numbers on the list.

IIRC the oil change interval is dependant on the kind of driving you do.
Most car makers recommend more frequent oil changes if the engine is
subjected to severe service -- the catch is that the definition of
"severe service" is what many of us would call "normal driving" -- short
trips, stop-and-go driving, dirt roads, etc.

Doug