I'm currently running 15W40 Rotella, dino not synthetic, changed every 5,000 miles. This next change I'm planning on going to Mobile 1 5W40, changed every 5,000 miles.

The "on clearance, buy it" part of me got the better of me.

I was not actually planning on trying to run the oil longer, at least not without a baseline of oil analysis to start with and then periodic sampling while running.

I do 90% highway driving. I was doing 500 miles up on Sundays, 70 miles of in town driving, then 500 miles back down on Fridays. Now I am doing 150 miles down, 20 miles in town, 150 miles back up, plus maybe 20 miles in town on the weekends.

My 1987 300D seems to be running well and I'm usually down about 1/2 quart of oil at the end of 5,000 miles.

I was planning on using 1/2 quart at oil change and not topping up between oil changes. I had assumed that this was a cannot hurt item. It might not help, but was not likely to hurt. Now I am wondering.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.