What LACTD said.
Dodge warranties the Cummins engine for 100,000 miles. If you buy that engine from Cummins & have it installed in a delivery-type truck (Snap-on Trucks, etc.), you get a 300,000 mile warranty. I don't believe Cummins would provide that warranty thinking that there is only a 50,000 mile "buffer" between the end of warranty & when the engine needs to be rebuilt.
Many of these million+ mile engines achieved that mark without "creative" oil & filtation products.
I know of one 94/95 Dodge, that hauled/delivered trailers all its life, with 1,153,000 miles that used Shell Rotella 15-40 with Fleetguard filters. OCI's at 5000 miles.
My understanding is that the oils of those days were not of the quality of todays oils. The Fleetguard filters, in those days were of cellulose construction. Nowhere near as good as todays Stratopore filtering media, which, makes this even more amazing.
The highest mileage Dodge/Cummins that I heard of, without an engine rebuild, was 1,250,000 miles.
I'm beginning to think the benefit of the use of fully-synthetic motor oils with by-pass filtration, with Cummins engines, is the extended oil drain intervals, which, would be quite a convenience for those that drive extreme numbers of miles.
These engines seem to be able to live long, productive lives with just the use of quality conventional HDEO's, filters & regular OCI's.
Joe F.(Buffalo)