I have a 2000 E430. I’m getting a white sludge material forming on my oil fill cap. Much like a head gasket leak when coolant mixes with the oil. My local Mercedes mechanic said that certain brands of synthetic oil cause this and it’s also a sign of the oil not being changed often. Is this correct? He recommended replacing a quart of motor oil with transmission fluid to clean the engine for about a 1000 miles!!! Is this safe? Should I do this?

Thanks, Matt

 

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I never heard of anything like that unless it was a large disiel engine (which some of them uses the same oil for the trans and engine.).
If that's the case why not go get the engine flushed and cleaned? And the oil changed? Did he check for a gasket leak? And what brand of oil did you you?

 

you have water in your oil possibly blown headgasket

 

If its a blown headgasket there is a test you can do on the water in the radiator that detects the exhuast gas seepage from the engine. If thats negative and the engine runs sweetly it might just be a slight build up of water & oil emulsion due to cheap oil or lack of oil changes.

I would go for an engine flush and good quality oil. Also make sure that the crankase breathers are not clogged as poor crankcase ventilation will cause white emulsion to form in the top of the rocker covers and on the oil filler cap . Not sure where the crankcas vents are on your model but all engines have one somewhere - check the manual - its often a simple gauze mesh or blocked breather pipe.

 

If you were saying that the motor was 3.2 (V6) liter then everything would have been perfectly normal. I am not sure how the oil filler looks like on the 4.3 liter though. The fillers are so tall that the condensation forms at the top of of the oil filler right where the oil cap is. This happens a lot more in the winter because of the cold weather and condensation forming at the top. No such thing happened with the I6 engines because the filler was flush. Again, I'm not sure if that is the reason in your 430, but you should get another opinion.