Well Tommy, from what I've seen they "appear" to be the same oil.
Delvac 1 5W-40 is badged for commercial use and indicates the appropriate HD diesel specs, including CI-4 and Cummins spec (I need CES 20078). The oil also is dual-certified to SL spec for gasoline service.
In the U.S. the smallest container is a gallon jug, about 3.78 litre. In Canada, something like Wally World (Wal-Mart) carries it in 4 litre jugs.
Mobil 1 Truck and SUV 5W-40 makes mention of "generic" HD diesel spec CI-4, and SL for gasoline motors. It comes in 1 quart bottles so that's a lot handier for a "small" truck.
Ever try to fill a passenger truck or car with a 4 litre jug or, God Help You, a 20 litre pail??
Anyway, Mobil 1 Truck and SUV is mentioned in this forum and somebody was nice enough to post a high-res photo. It certainly looks like Delvac 1, since no other Mobil 1 product carries the CI-4 spec.
Mobil 1 0W-40, rated B4-02, is designed for certain light-duty European diesel motors and some high-performance European gassers like Porsche and BMW. It's only rated CF so there is no current North American diesel motor you could use it in.
Like I mentioned, although I use Mobil 1 10W-30 in summer, I do plan on using either Delvac 1 or Mobil 1 Truck and SUV starting in April. I have a couple of trips planned to Utah and Nevada in June and August, so that should give the oil a fine workout.
Anybody have any thoughts on this??
Jerry