I picked up an 05 E320 with 192k miles recently that I was able to get very cheap. It needed engine and transmission mounts and the original owner thought it needed an engine because of the vibration. Anyway, the engine has got some sludge build up that I figured would eventually clean up running Mobil 1, 0W40. I changed the oil right before the wife went on a 1200 mile trip and when she returned it was indicating to add a qt of oil. My question is if the rings are sludged up will the Mobil 1 eventually clean it up and reduce the oil consumption. The majority of the 1200 mile trip was at 80 mph.

Heck, I've got a 95 E300 with 309k miles and it only uses a quart about every 5k miles. I run it on Mobil 1 Truck and Turbo diesel or whatever it is called nowadays.

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Jim