FYI, Mobil 1 Truck and SUV is the same formula as Delvac 1 used in semi trucks, just in quarts instead of gallons. Its great stuff, but I would still stick to your normal change intervals. I havent seen any claims for the 15K changes on the diesel oils, only on the gassers.

To save money on oil, buy delvac 1 in larger quantities. Smallest is a box of 4 one gallon containers (around $100). Next is a 5 gallon jug. Pretty sure a 55 gallon drum is the next increment. I have yet to find Delvac 1 in single gallons. Delvac partial synthetic is common in gallons (black jug)

I usually keep a quart of Mobil 1 Truck and SUV in the trunk and buy the 4 one gallon box at a Mobil distribution center in Detroit.

But my engine has been using fully synthetic since day one, if you havent been using fully synthetic, some oil leaks may occur.

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2002 VW Golf TDI-169,000 miles B20