The short answer
Keep clean fuel going in, use the oil and coolant Ford specifies for your model year, drain the water separator, keep the driveline fluids fresh if you tow, and treat the DEF and emissions parts with respect. Start with your truck’s model year, mileage and service records, then work out what is due next.
After 12 years as a Ford dealership service advisor, my starting point for 6.7L maintenance is simple: know what is due for your truck, do it on time, and keep a record of it.
This is not a full maintenance schedule. The schedule in your owner’s manual changes by model year and by how you use the truck, and it is the final word on intervals. This is the short list of jobs I would never let slide on a 6.7L, and why each one matters.
1.Both fuel filters, as a pair
The 6.7L uses two fuel filters. One sits in the diesel fuel conditioner module on the frame, next to the fuel tank. The other is mounted on the engine, under the hood. It is easy to remember one and forget the other. Change them together.
The reason is the high-pressure fuel system. It does not tolerate water or dirt, and a fuel filter costs far less than a contaminated fuel system.
After a filter change, prime the system the way Ford describes: turn the key on for 30 seconds, then off, and repeat. That is in both the 2017 and the 2026 owner’s manuals.
Pro tip
Use filters that match the factory part. A filter that “fits” is not always a filter that filters to the same standard.
2.Drain the water separator
The frame-mounted fuel conditioner module has a water separator with a drain. When the truck tells you there is water in the fuel, do not ignore the message. Drain it with the engine off, and catch the fuel in a container. Then prime the system, and think about where you filled up last.
Draining it during oil changes is a good habit even without a warning. It takes a few minutes and you see right away if something is wrong.
3.Ford-spec oil, on the right schedule
Ford does not just ask for “diesel oil”. It asks for oil that meets Ford specification WSS-M2C171-F1. The 2026 manual lists Motorcraft 10W-30 as the main oil, with 15W-40, 5W-40 and 0W-40 listed for cold weather, biodiesel or severe use. Look for the Ford spec on the bottle, not only the viscosity.
Follow the oil life monitor. If you tow, idle a lot, drive in dust or make many short trips, also follow the special operating conditions schedule for the other items.
4.Two cooling systems, and the right coolant for your year
The 6.7L has a primary cooling system and a secondary one. Both need the correct coolant at the correct level, and both have hoses and connections to inspect. The second reservoir is easy to miss.
The correct coolant changed over the years. The 2017 manual calls for Motorcraft Orange Prediluted. The 2026 manual calls for Motorcraft Yellow Prediluted. Do not guess and do not mix types: check the manual for your exact model year.
Never open a hot cooling system. Let the engine cool down fully first.
5.DEF, and letting the emissions system do its job
Diesel exhaust fluid is simple stuff, but it is easy to ruin. Buy sealed containers, keep them out of direct sun and heat, and never put anything else in the DEF tank.
If DEF ever goes into the diesel fuel tank, do not start the engine. The 2026 owner’s manual says the tank must be fully drained and cleaned first, and it warns of fuel pump and injector failure that the warranty may not cover. Call for a tow instead of turning the key.
Your truck also cleans its diesel particulate filter (DPF) on its own, often at steady highway speed. Lots of very short trips can keep it from finishing. If your driving is mostly short hops, a regular longer drive helps. When the truck shows a cleaning message, let it finish instead of shutting the engine off again and again.
6.Transmission, axle and transfer case fluids
The engine gets the attention, but a truck that tows puts a lot of heat into the transmission, the axles and, on a 4×4, the transfer case. These fluids are easy to forget because nothing tells you they are tired until something is wrong.
If you tow, plow or haul heavy loads, these services often fall under the severe use schedule. Have them checked on that schedule, and ask for the fluid that matches the factory specification.
7.Air filter, belts and hoses
A diesel moves a lot of air. A dirty air filter costs you power and fuel, so check it more often on gravel or dirt roads. While the hood is up, look at the belt for cracks or glazing, and squeeze the hoses. Soft, swollen or cracked hoses are cheap to replace in your driveway and expensive to replace on the side of the highway.
Signs something needs attention now
Some things should not wait for the next scheduled service:
- A water-in-fuel message that keeps coming back after you drain the separator.
- A coolant smell, or coolant levels that drop between checks.
- Hard starting, rough running, or a loss of power under load.
- DEF or emissions warnings that do not clear.
- Smoke that is new for your truck.
Do not wait for the next service appointment. Ask a qualified diesel technician about any new warning or symptom.
Keep a record
Write down every service: date, mileage, what was done, and which parts and fluids went in. It keeps you on schedule. It helps any shop that works on the truck. And when you sell the truck, a clean record helps the next owner trust it.
Want a guide and a place to record your maintenance? Take a look at my Ford 6.7L Power Stroke Owner Guide and maintenance tracker bundle.
The bottom line
Do the basics on time, with the parts and fluids Ford specifies for your model year. That is what keeps a 6.7L working the way it should.
