Personally, I can't stand Rotella . . . doesn't have enough detergent in it. I am a truck driver and have seen engines pulled apart with regular changes/maintenance, and they were the filthiest engines with shavings and gunk stuck to the walls of everything!!! If the car has been sitting for awhile, I would use the Castrol 15/40, as it has the ability to suspend all that stuff into the oil for the filter to pick up. You may want to change the filter after 500 miles to insure that you have clean filter after all that stuff was picked up off the engine.

Otherwise, I prefer using Chevron Delo 400, as it is the thickest oil that doesn't thin out when the engine is running warm from climbing hills . . . almost like having Lucas stabilizer built in!!! Mobil Delvac is a blended oil that is compatible with synthetic, as well as regular oil and also has an excellent reputation. There is also the "blue" (forgot the maker) that is also good, and you can always go to the tractor store/Walmart and use the 2-gallon jug (and it's cheap!!!) which has served me well on both Peterbilt and my car.

Not to knock Shell Rotella, as their product is the only approved for running in Catepillar Engines (very high torque engines), but outside of the Cat line of engines, I think other brands are better and cleaner.

IMHO

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1983 300D, the "Avocado"
1976 240D, 4-spd the "Pumpkin", SOLD to Pierre
1984 190D, 2.2L, 5-spd, my intro to MBZ diesels, crashed into in 2002