Diesel Pickups: More Oil, Different Specs, Same Drive-In Lane

Cummins-powered Rams, Power Stroke Super Dutys and Duramax Silverados and Sierras do the heavy work across Northern Nevada: horse trailers in Washoe Valley, fifth wheels heading for the Eastern Sierra, contractor rigs on new subdivisions south of Reno. A diesel oil change looks like any other from the driver's seat, but the oil, the volume and the schedule are all different. Here is what changes, what the makers and the American Petroleum Institute publish, and what we do with a diesel in our bay.

At a glance

• API CK-4 is the current heavy-duty diesel category; FA-4 is a separate lower-viscosity category not meant for every engine (API)
• Ford's 6.7L Power Stroke calls for oil meeting Ford specification WSS-M2C171-F1
• A 6.7L Cummins takes about 12 quarts with a filter change (Bulletproof Diesel capacity guide)
• Washoe area: diesels up to 14,000 lb GVWR are smog tested yearly; heavier diesels are exempt (Nevada DMV)
• Towing keeps most diesel pickups on the severe schedule

The oil is a different product

Diesel engines make soot, run high cylinder pressures and spend long hours under load, so diesel oil carries more detergent and dispersant and a different additive balance than a gasoline oil. The American Petroleum Institute's motor oil guide lists the heavy-duty diesel categories under the letter C. CK-4 is the current main category and is designed to be used in place of older categories such as CJ-4. FA-4 is a separate category with a lower high-temperature viscosity, intended for certain newer on-highway engines, and it is not interchangeable with CK-4 in every truck.

The truck makers layer their own requirements on top. Ford introduced specification WSS-M2C171-F1 for the 6.7L Power Stroke, and Chevrolet's owner pages call for 15W-40 diesel-rated oil for the Duramax and dexos2 for its light-duty diesels. Ram's manuals name a Cummins-approved oil and a grade such as 15W-40. We read the spec from the manual or the cap and pour the matching diesel oil, never a gasoline oil in a diesel.

More quarts and a bigger filter

Volume is the first thing customers notice. Bulletproof Diesel's capacity guide lists the 6.7L Cummins at about 12 quarts with a filter change and the 2011 to 2022 6.7L Power Stroke at about 13 quarts, with later Power Strokes higher. A typical gas sedan holds around five. The filter is larger too, and on some engines it sits in a housing on top of the engine with a cartridge element instead of a spin-on can.

We fill to the capacity the manual gives, run the engine, check for leaks and confirm the level on the dipstick before you drive off. Our diesel oil change page covers the oil side in more depth.

The diesel smog rule in Nevada

The Nevada DMV's emission control program tests diesel vehicles in the Washoe and Clark County testing areas when they are rated up to 14,000 pounds gross vehicle weight. Diesels over 14,000 lb GVWR are exempt. Most three-quarter-ton and one-ton pickups fall under that line, so a Reno-registered Ram 2500 or F-350 is usually tested every year after its first three registrations, the same as a gas truck. Your GVWR is on the sticker inside the driver's door.

Carson City, Douglas County and Lyon County do not require smog checks for registration, so a diesel registered in Gardnerville or Dayton does not need one. If you are in Washoe and due, our Reno service centers can help, and you can read the full rules on our Nevada smog check page.

Towing, idling and the high desert

Most diesel pickups here tow, and towing, long idling and dusty roads are exactly what the severe schedules are written for. The oil life monitors on current Ram, Ford and GM diesels weigh that kind of use and shorten the interval on their own. Long idle periods at a job site or a cold-morning warm-up add engine hours without adding miles, which is why some diesel schedules count hours as well as miles.

Winter matters for diesels in particular. Minden averages about 188 nights a year at or below freezing and about 75 at 20 F or colder (NOAA 1991 to 2020 normals), and a diesel that cranks slowly on a cold morning is often telling you about its batteries. Many diesel pickups carry two. We test them at participating locations as part of the multi-point maintenance check, along with the air filter, coolant, differentials on request and the transmission fluid where the design allows.