Car has done 115K, and is consuming one quart of oil per 1000 miles. If worn valve stem seals are rules out (never blue smoke, no smoke whatsoever), what other causes could there be? Oil scrape rings?

Cheers?

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2011 Prius

You won't necessarily see blue smoke or see oil on your spark plugs if the valve stem seals are worn. I had mine changed a few months ago when the head gasket was also replaced. Oil consumption went from about what yours is to maybe 1/2 qt. every 2000 miles.

A 30 yr. MB veteran at another MB web site once said that 103 motors are going to use a little. If they don't, somethings wrong. It's been my experience that European cars are not as oil tight as Asian cars. 1/2 qt. every 2000 sure beats 2 qts every 2000.

My 2 cents.

Another issue is how full you fill the crankcase. Many MB engines will use more oil if you try to top them off. The factory has issued a TSB about this and recommends filling them only to the point halfway between full and one quart low.

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Steve
'93 400E

Thanks lads.
Read some threads on higher consumption due to using (semi) synthetic oil. M102s were developed in pre-synthetic times, and their seals do not agree well these new oils, they state.

Am considering returning to mineral oil.
Any thoughts?

Cheers!

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2011 Prius

I'd be extremely surprised your problem could be totally solved by returning to mineral oil.
I'd try a heavier oil grade (ex: 20W50). If it does not work, time for new valve seals. A few hundreds $$ would do it.
If it still not solve the problem, then go to the valve guides. Much more $$ though.
Good luck
jackD

I would agree that synthetic oil is not likely to be the problem. From my reading, I believe synthetics produced in the last 15 years or so have taken seal composition into account so the issue of "synthetics make my previously tightly sealed engine leak like a sieve" are really irrelevant.

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Steve
'93 400E

Re: synthetics and leaks:

I've found quite the opposite. I put synthetic oil in the "old" chevy work van -- 297,000 miles, used about a quart every other tank of fuel. After I filled up with synthetic, oil consumption dropped to zero in 3000 miles. Most of the oil seems to be going down the valve guides -- blows some blue smoke on startup and occasionally needs some "help" starting hot (staring fluid).

I put synthetic in the 300TE last year, and oil consumption dropped quite a bit. I've not tracked very well, since it is my mother's car, but I've only added one quart since, she has put in one, I think.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!