Diesel Pickup Oil Change Intervals: Power Stroke, Cummins & Duramax

The single most important thing you can do for a light-duty diesel is change the oil on time with the right oil. Diesels run hotter, generate more soot, and put far more stress on engine oil than a gas engine does — which is exactly why the interval and the oil spec matter more here.

The short answer

For most modern 3/4- and 1-ton diesels under normal driving, the manufacturer interval lands between 7,500 and 10,000 miles. Under severe service — frequent towing, heavy loads, lots of idling, short cold-weather trips, or dusty conditions — that drops to roughly 5,000 miles or the oil-life monitor, whichever comes first.

Engine	Normal interval	Severe / towing
Ford 6.7L Power Stroke	up to 10,000 mi	~5,000 mi
Ram 6.7L Cummins	up to 15,000 mi (oil-life monitor)	follow monitor, often ~5,000–8,000 mi
GM 6.6L Duramax	up to 10,000 mi (oil-life monitor)	follow monitor

Always defer to the oil-life monitor and your owner’s manual for your specific year — these are ballpark figures, not a substitute for the OEM spec.

Why the interval is shorter than you’d think

Diesel combustion produces more soot, and some of it ends up in the oil. Soot thickens oil and accelerates wear. Fuel dilution from post-injection events (part of how the truck cleans its particulate filter) also shears the oil down over time. The result: oil that looks “fine” can already be out of spec.

Use the right oil

Run a diesel-rated oil that meets your engine’s spec — typically a CK-4 full-synthetic in the viscosity your manual calls for (often 5W-40 or 10W-30 depending on engine and climate). The Lowcountry rarely sees deep cold, so most owners here are fine on the warmer end of the range year-round.

Severe service is more common than you think

If you tow a trailer to the boat ramp on weekends, sit in Charleston traffic, or take a lot of short trips where the engine never fully warms up — you’re in severe service, not normal. Use the shorter interval.

Pulling samples for an oil analysis once or twice a year takes the guesswork out of it and can safely extend or confirm your interval.

A late oil change is one of those things that costs nothing to get right and a fortune to get wrong.