Cummins says 15K or 12 months which ever occurs first. They go further on the same page and say 7500 or 6 months for every day driving
. I'm not sure what all that means.
For me, our last oil change was August 14, 2012, 45,000 miles, for some reason I thought we had changed the oil in April last year. So IM golden on this issue, we have 4500 on the oil change according to the paperwork and the odometer.
What is confusing is that oil change places always want you to change oil at an earlier interval than what the manufacturer recommends. Diesel mechanics aren't any different.
Here is a linky to the info I got
Cummins Diesel Maintenance Schedule