Let's see ... that is $1.50 differential per quart times the number of quarts? Say, about $10 per oil change, tops?

Just my 2c, but seems like going part way ...

If cost and/or time were issues I would probably go with petro base with max additives at a differential of $3.00 per quart.

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George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg