If you have a place to send in oil samples for analysis that would be the best way to see how long you can go on a service. Also by hour is better than by milage. If you have nowhere to send samples, figure your service on driving habits and oil (conventional, synthetic, long trip, short trip, dusty roads, hauling a heavy load, temp outside,ETC) I have a 06 cummins and run full synthetic, change my oil at 10,000 when the truck is getting worked, and 12,500 to 15,000 under normal use. I am a truck and equiptment mechanic and the only problem I see with extended drain intervals is the lack of mantinance on the rest of the truck. In that 10,000-15,000 miles I change a fuel filter and clean my air filter, check all the boxes, trans fliud, ps, and coolant. Just remember you probably won't have a major engine problem under your warranty.( not saying it can't happen ) If you plan on keeping the truck over a 100,000K oil is cheap engines are not. It may be overkill to change at 5,000-7,000 but it is safe.
