Any possible oil-related question always brings up countless opinions and here's mine.

First, Mercedes-Benz says no engine flushes or snake-oil should be used. Ever. Further, if your engine has not had a pure synthetic oil (on the MB tested and approved list) since it was new, this might be related to your problem.

Since at least 2001, factory fill on all MBs coming to the US at least, has been Mobil1 0W40, changed according to the FSS at a minimum of 10000 miles. And, even though I know full well that I can keep it in my own M112 powered C320 that long, I change it at 5000 miles.

Additionally, the '05 and later cars have abandoned FSS and gone to a straight 13000 mile oil change using M1 0W40 Extended Performance using a fleece filter.

One last, if your lifter repair was performed by a dealer, you have a warranty on the job so you should go back to complain.

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Roger E.