Intervals follow your duty cycle
The Cummins X15 quick reference guide sets oil drain and filter intervals by duty cycle and fuel economy rather than a single number for everyone. Work out which category you are in honestly: heavy-haul, mountain and vocational work lands in the shorter intervals.
Aftertreatment
- Long idling and low-speed work load up the DPF. CARB's guide for drivers stresses letting regens complete.
- Certified DEF only, and keep the fill area clean.
Records pay
Oil analysis reports, filter changes and aftertreatment service records support warranty claims and resale.
Where this comes from
- Cummins: X15 quick reference guide (PDF)
- California Air Resources Board: Truck driver's guide to DPF care (PDF)
- Cummins: DEF quality and maintenance (PDF)
- API: DEF do's and don'ts fact sheet (PDF)
Last reviewed 2026-10-19. General information only: your owner's manual and service information come first.