This car has 415k miles. The engine runs great, starts up on a dime. Its a little weak on power at slower speeds, but when I get her up to speed it flys. Regradless of driving speed or style, the engine is burning a lot of oil (in my opinion). Consumption is about 1 QT every 600 miles. There is also lots of blowby in the engine, when I loosen the cap is dances a little bit and oil seeps out of the cap. I tried replacing the cap with multiple brands even OEM with no avail.


My brother in law who is a diesel mechanic recommend me put marvel mystery oil in the engine oil to have it soak the pistons. I am really hesitant about doing so. But he swears on this stuff.

Any thoughts? Should I do it?

Soak the pistons from the top for a couple of days if you can, replace the valve seals. If not going to do valve seals add LubroMoly Oil Saver to soften the seals.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Also remember that you could be leaking it

Any oil in the exhaust.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

I can smell diesel/oil in the exhaust

Remove the Injectors or the Glow Plugs if you can find a way to get the marvel mystery oil into the Cylinders and let it soak for a week and repeat it. This only works if your rings are stuck.

I don't agree on dumping the marvel Mystery Oil into the Engine oil as it will just thin it out. People have said full synthetic oil and driving for 300 miles or so will free up stuck piston rings.

If you simply must dump the marvel mystery oil into the Engine Oil use straight 40 weight oil so the marvel mystery oil does not thin the oil out too much.

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84 300D, 82 Volvo 244Gl Diesel

A compromised turbo seal is a possibility

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

The helpful posts here hit most of the bullet points. I agree that marvel mystery oil is great as is lacquer thinner if the problem is stuck rings which unfortunately it may not be. If the air filter wasn't frequently changed and/or oil changes done as recommended then the engine may just be worn out, worn rings, valve guides/seals etc. A compression test is in order if you decide to pour something to treat the rings. It would be nice to do a before and after soak. I have done that once and saw little to no difference. My guess is that the engine is probably worn but with good maintenance it may only last another 1 or 2 hundred thousand miles more.!!! rebuilding these engines is very expensive but if you can hone in on the main problem it may be affordable depending upon what the problem is. A quart every 600 is nothing, live with it.

Try running straight 40weight oil. As the weather warms. Substantial decrease in oil consumption it is general wear usually. Also only fill oil to the halfway point of the dipstick marks. A lot of reports these engines will burn oil down to that point.

As mentioned a turbo seal or leak is another possibility. Yet at that millage with perhaps neglected oil changes wear is the strongest possibility.

It is also a misteak to assume the odometer has not broken at one time or been tampered with on these particular cars.So true total millage can be elusive.Worse model car ever for odometer tampering in the day.

Good point, I'd forgotten about that. Don't try to chase the full mark on the dipstick, aim for the midpoint. At the full mark, these OM61x engines are known for burning up the excess and if you keep adding oil to the full mark, the engine will keep burning it up.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC