I just recently had my oil and filter changed... I went close to 8,000 miles this time, procrastination the last 2k miles.
Anyway, my mechanic said that the oil definitly needed to be changed, "It was time." ...as in the oil was plenty dirty.
In the crankcase was fully synthetic mobil 1 oil, 20w50 I believe. I consider my driving characteristics between "severe" and "normal" on an oil changing scale. I usually drive more than 15 miles per trip, always warming the oil/engine completely, thus every day burning the contaminants off the oil. But I also drive hard.... with many high revs, and a lot of 3,000 + rpm freeway driving.
This is in my 1995 C280 with 125k miles.... and tuned properly.
So what does this say?
I think that a nice balance between the "fanatical" and "extended" beliefs will work just fine for me; DEFINITLY less than 8,000 miles (my longest stretch yet).
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)