ohcaptainron,

I am not sure what the "rules of thumb" cited are based on, and, considering my experience Mercedes-Benz is not about to reveal the causes and facts. My 1991 350SD was at about 160,000 miles when symptoms started, and by 162,000 I had it in to rebuild the engine. I bought the car with 75,000 miles on it expecting it to last for several hundred thousand miles, and I never put anything but Mobil 1 15W-50 in the engine. I changed the oil on a regular basis, usually every 3,000 or 4,000 miles and never went longer than 6,000.

On the other hand, if you get one of these cars in great shape for a good price, and you are mentally ok with the potential for the engine to suddenly die, you may be very happy with the car. Until the engine failed, I was extremely satisfied with the car - great ride, lots of room and very good mileage. I was not ready for mine to die when it did and will never feel a newer Mercedes-Benz is quite the machine the older ones were.

I know that sounds like a cliche' but some of those '70's and '80's cars were just as close to bulletproof as a car can be, simple maybe, with fewer gadgets, but unbreakable. I am often struck by how we have come to accept or even demand useless gadgets in our cars. It is at the point where the engine, transmission and chassis are taken for granted and hardly affect the selection process of a new car buyer. The car itself is now merely a means to sell electronic junk that no one would buy if it was not in a car.

Given knowledge of the issues here, you can make an informed decision. That is a better position than most of us with first hand experience with the 3.5 liter Diesel failing were in when we bought. Good luck whichever way you go, 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)