With approx 100K miles on the clock, the engine suddenly began to use approx 1qt of oil for every 600 miles. Prior to this, the dipstick typically read a shade under 1 qt low at every service interval (5000 mi)

I can't imagine its suddenly broken a oil ring... there has got to be a vaccuum port pulling oil over somewhere...

Any thoughts?

ob1jeeper,

It is a relatively common problem for cars of your vintage and engine type to need valve seals by the mileage you are showing, or earlier. This was so common, in fact, that MB developed a set of procedures for most cars without removing the head. If you do a search on valve seals you may get some added information, including some do it yourself hints. Good luck, and I hope this helps. Jim

__________________
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)

The valve guide oil seal problem is so pervasive and so easy to solve that it ought to be included at 100k servicing IMHO. The 2 to 2.5 hours it takes combines readily with spark plug removal and valve cover resealing (leaving only an hour or hour and a half extra labor) which would already be part of a large service done around that time (maybe the 120K service).

The rings are never the problem!

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician