This is what I use. Endorsed and recommended by Cummins so figure if there was ever an issue I used the oil they recommended.
With that said you really can't go wrong with any of the well known brands in my opinion. Oil analysis has proven it is holding up just fine in my truck at 15K change intervals.
I use Rotella T6. Because I live in a cold climate, Cummins wants a synthetic in the engine. I always find a deal on it just after the first of the year and buy enough for the RAM plus my land maintenance equipment.
Blackstone has a paper out that is a summarization of individual's oil analysis that compares various oil labels of the same type. Interesting read, don't have the link for it since I read it from a link on another forum but should not be hard to find. The bottom line, there is little difference in engine wear between the oil brands.
The reason why Cummins recommends Valvoline is because they have a contract with them for their factory fill oil and other lubricants. Basically, Cummins endorses them because Valvoline reduced the cost of their factory oil and other lubricants used to make their engines. Kind of a you scratch my back and I'll scratch yours deal. Many manufacturers do this to cut costs.
And doing the oil change is not that bad, head to Geno’s website and order the fleet guard stratopore filter, the filter cap for when you pull it so you don’t spill the filter pulling it out the hole in the fender liner, and to make it easier and less messy for the next. Get the oil pan drain that screws into were the drain plug goes in, it makes it stupidly simple to drain, and if you have a 5 gallon bucket with a pop up pour spout, you can drain it right into the bucket. Let it keep dripping as you go inside and have lunch, come out. Snap it closed and not have any oil anywhere but in the jug!