John Deere Plus-50 Supreme. Supposedly one of the best dino diesel oils out there. Have used it in all of our diesels for years, including my 190D for the past 100K +.

Jim

PS - the 300SD will usually be down 1/2 qt between 3K changes,

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2005 C240 4matic wagon (daily driver)
87 190D - 225K (on loan)
85 190D - 312K (on loan)
2011 Subaru Legacy AWD (Wife's)