what you need to look at is the api classification on the oil your buying. Different api classes are set up for different engines. Oils that are approved for diesels may resist break down from the fuel that always slips past the rings in our diesels.

I have been running the Rotella 15w40 in all my vehicles, including my Ranger V6, and several Benzes, one with over 300k on it. Ive had no problems with any of them running the Rotella. If you know anyone that has a membership in the Mercedes Benz club, thier rag has an article called the oil spot. In it they show the recommended oils for benzes gas/diesel and so on. I'm very happy with the Rotella and after a 2200 mile trip in my '82 wagon with 300K on it, the entire trip even back through the Allegheny mountains of PA she used LESS then a quart of oil.