I agree I would rather use the Mobile 1 also, I just could not find it for a long time, so I went to the Rotella. Now that I have been running it I think I am going to stay with it. After reading tons and tons about the two oil comparisons the slight advantage that Mobile 1 gives is not worth it to me. After I could not find it I researched Rotella T heavily.
My costs are a little higher because I am using it in two cars, but the TDI is 10k change and the Mercedes is a 5k change.
That being said I am a advocate of everyone using what ever oil they want and changing it when ever they want, it keeps everyone happy. I am just glad to see there is another oil I like on the shelves at wallyworld.

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1999 E300 TD 190,000
1996 Passat TDI 225,000-sold
1996 E300 120,000-sold
1998 Jetta TDI 186,000 -sold
1983 Chev Suburban C20 6.2-sold