I appreciate your effort and info you've provided about the changes Mobile 1 is going through. I looked at a 1 qt. container of the new Super Syn 15W-50 at Wal Mart and, significantly, the label did not say it was M-B approved as is the Tri Synthetic formula in 15W-50 (I did not look at the other weight categories for the Super Syn).
What do you think of using the old Tri Synthetic formula 15W-50 in my '77 300D? I just rebuilt the diesel engine myself about 2,000 miles ago and will change to a synthetic oil at the next oil change (break-in with Chevron Delo 15W-40). The Tri Synthetic formula has a CF API rating which should work in my engine and I like the 15W-50 because I live in Texas where high temps are almost here. Also, I can buy the Tri Synthetic at Wal Mart for $17.88 in a 5 quart jug (what's left of the old stock) in enough quantity for 3 oil changes (about 1 year) - and then see how things shake out with some of the newer diesel synthetic oils now being introduced. The Tri Synthetic 15W-50 also has better specs than the Chevron 5W-40 synthetic you recommended for diesel engines (except it carries the CH-4 rating which I do not believe has any benefits for my older engine), as well as other synthetic oils for diesels I've looked at, which is why I'm leaning toward buying the remaining Tri Synthetic stock at Wal Mart.
Any comments you have will be appreciated.
America: Land of the Free!
1977 300D: 300,000+ miles
American Honda: Factory Trained Technician & Honor Grad.
Technical Advisor to Am. Honda;
Supervisor of Maintenance largest tree care co. in US for offices in Tex.