GMC Sierra 2500HD Duramax Maintenance Schedule: 2024–2026 6.6L Diesel Service Intervals
GM’s schedule for the 2024–2026 GMC Sierra 2500HD 6.6L Duramax Turbo-Diesel V8 puts the truck’s monitors first and the odometer second. Check the engine oil level and oil-life percentage every 7,500 miles. Change the oil when the oil-life system calls for it, or at least once a year. Replace the fuel filter every 22,500 miles or two years, whichever comes first. Trucks that tow often follow GM’s severe-service schedule. That schedule adds an Allison transmission fluid and filter change every 45,000 miles.
These intervals come from the GMC Sierra HD owner’s manual and GM’s 6.6L Duramax Diesel Engine Supplement. In these trucks the Duramax makes 470 horsepower and 975 lb-ft of torque and pairs with the Allison 10-speed automatic. GM notes that damage caused by improper maintenance may not be covered by the vehicle warranty. For 2027, GM introduced a new 8.3L Duramax; this guide covers the 6.6L.
6.6L Duramax Sierra 2500HD Maintenance Schedule at a Glance
The owner’s manual splits the schedule into normal service and severe service. The table lists both. If a Driver Information Center message appears before the mileage shown, act on the message first.
| Service | Normal Service | Severe Service |
|---|---|---|
| Engine oil and filter | Check level and oil life every 7,500 miles; change when the oil-life system calls for it, at least once a year | Same rule; the oil-life indicator may call for a change before 7,500 miles |
| Tire rotation and Multi-Point Vehicle Inspection | Every 7,500 miles | Every 7,500 miles |
| Fuel filter | Every 22,500 miles, two years, or at the CHANGE FUEL FILTER message | Same; may need replacing sooner with biodiesel, dust, off-road driving, or extended towing |
| Passenger compartment (cabin) air filter | Every 22,500 miles or 24 months | Every 22,500 miles or 24 months |
| Engine air filter | When the Engine Air Filter Life System message appears | When the Engine Air Filter Life System message appears |
| Automatic transmission fluid and filter | No scheduled interval | Every 45,000 miles |
| Transfer case fluid (4WD) | Every 50,000 miles | Every 25,000 miles |
| Brake fluid | Replace every five years | Replace every five years |
| Engine cooling system (drain and fill) | Every 150,000 miles or six years | Every 150,000 miles or six years |
| Hood and/or body lift struts | Every 100,000 miles or 10 years | Every 100,000 miles or 10 years |
| Air conditioning desiccant | Every seven years | Every seven years |
The information in this article is general guidance and does not constitute a specific diagnostic or repair recommendation for any individual vehicle. Repair and maintenance decisions should be made in consultation with a certified technician based on the specific condition of your vehicle.
What the 7,500-Mile Visit Includes
The 7,500-mile visit pairs the tire rotation with a Multi-Point Vehicle Inspection. That inspection checks fluids, belts, hoses, brakes, and the battery. It also includes chassis lubrication.
Power Take-Off and Extended Idle Use
Some trucks run power take-off (PTO) equipment or idle for long stretches. The owner’s manual counts each hour of that use as 33 miles toward the schedule.
Does Your Sierra 2500HD Need the Severe-Service Schedule?
GM’s severe-service column applies to trucks that are:
- Mainly driven in heavy city traffic in hot weather
- Mainly driven in hilly or mountainous terrain
- Frequently towing a trailer
- Used for high-speed or competitive driving
- Used for taxi, police, or delivery service
North Texas summers run hot. The National Weather Service in Fort Worth puts the average first 100°F day at Dallas/Fort Worth on July 1. If your Sierra 2500HD regularly pulls a trailer or works stop-and-go traffic in that heat, plan around the severe-service column.
6.6L Duramax Fluids and Capacities
The Duramax supplement lists the fluids the diesel needs. Here are the ones covered on this page.
| Fluid | What GM Specifies | Capacity or Interval |
|---|---|---|
| Engine oil | API CJ-4 or CK-4; SAE 15W-40 (SAE 5W-40 below 0°F) | 10 quarts with a filter change |
| Automatic transmission fluid | DEXRON ULV | Change with the filter every 45,000 miles under severe service |
| Diesel Exhaust Fluid (DEF) | Check the DEF percentage at each fuel stop | About 7 gallons (2025 model year) |
What Oil Does the 6.6L Duramax Need?
The 6.6L Duramax holds 10 quarts of oil with a filter change. GM requires diesel engine oil with the API CJ-4 or CK-4 designation. It specifies SAE 15W-40 viscosity. Below 0°F, GM recommends SAE 5W-40 for easier cold starts.
Oil without the CJ-4 or CK-4 designation can damage the diesel particulate filter (DPF). GM says that damage would not be covered by the warranty.
When the Driver Information Center shows CHANGE ENGINE OIL SOON, change the oil within the next 600 miles. Reset the oil-life system after every change. For filter part numbers and oil specs by model year, see our GMC Sierra HD oil type and capacity guide.
How Often Should You Replace the Fuel Filter and Check DEF?
Fuel Filter
Replace the fuel filter every 22,500 miles or two years. Replace it sooner if the CHANGE FUEL FILTER message appears. The Driver Information Center shows Fuel Filter Life Remaining, so you can track it between visits.
The Duramax supplement says the filter may need replacing more often in some cases. These include biodiesel use, dusty climates, off-road driving, and towing a trailer for extended periods.
Diesel Exhaust Fluid (DEF)
Diesel Exhaust Fluid works with the exhaust aftertreatment system to reduce emissions. The DEF tank holds about 7 gallons on the 2025 model year. GM does not publish a DEF refill interval. Instead, check the DEF percentage at each fuel stop. Range warnings first appear at about 500 miles of remaining DEF and again near 300 miles.
What Maintenance Does the Allison 10-Speed Transmission Need?
GM’s normal-service schedule sets no mileage for changing the Allison 10-speed’s fluid. Under severe service, the owner’s manual calls for an automatic transmission fluid and filter change every 45,000 miles. GM specifies DEXRON ULV automatic transmission fluid. The transmission is also checked for fluid condition and leaks during each Multi-Point Vehicle Inspection.
On 4WD trucks, change the transfer case fluid every 50,000 miles under normal service. Under severe service, change it every 25,000 miles.
How Does Heavy Towing Change Your Maintenance Plan?
Frequent towing moves a Sierra 2500HD onto GM’s severe-service schedule. In practice, that means:
- Oil: The oil-life indicator may call for a change before 7,500 miles. Follow the indicator, not the odometer.
- Transmission: Change the fluid and filter every 45,000 miles.
- Transfer case: Change the fluid every 25,000 miles on 4WD trucks.
- Fuel filter: Extended towing can shorten its life, so watch the Fuel Filter Life Remaining display.
- Engine air filter: Replace it when the Engine Air Filter Life System message appears.
- Brakes: The brake system is checked at every Multi-Point Vehicle Inspection.
You can request filters and fluids through our parts order form.
Common Questions About Sierra 2500HD Duramax Service
What happens if the DEF tank runs empty?
As DEF runs low, the Driver Information Center displays warnings, starting at about 500 miles of remaining DEF range. If the warnings are ignored and the tank empties, the display shows the distance until vehicle speed is limited. The limit is applied in steps. Refill at the first opportunity after a low warning to avoid speed limitations, as the Duramax supplement advises.
Can I change the Duramax fuel filter myself?
The Duramax supplement places the fuel filter under the truck on the driver side, inside the frame rail. After a filter change, the fuel system must be primed with its electric priming pump. Turn the ignition on for 30 seconds without starting the engine, then follow the restart sequence in the Duramax supplement. Reset the fuel filter life monitor when you finish. GM advises leaving the job to a trained technician if you don’t have the right tools and information.
The information in this article is general guidance and does not constitute a specific diagnostic or repair recommendation for any individual vehicle. Repair and maintenance decisions should be made in consultation with a certified technician based on the specific condition of your vehicle.
Does the 6.6L Duramax need a fuel additive?
In the Duramax supplement, GM highly recommends TOP TIER Detergent Diesel. Where it isn’t available, GM recommends ACDelco Diesel Fuel Conditioner and does not recommend other aftermarket diesel additives. The truck has a fuel heating system to help prevent gelling. Below 32°F, GM advises avoiding biodiesel blends above 5%.
How do I know the DPF is cleaning itself?
According to the Duramax supplement, the diesel particulate filter cleans itself during normal operation, roughly once per tank of fuel. Idling and very short trips can keep the process from finishing. If a DPF message appears, drive at a steady speed as close to the posted limit as is safe until the message turns off. That can take up to 30 minutes.
What warranty covers the Duramax engine?
GMC Sierra 2500HD and 3500HD pickups from 2016 onward with the 6.6L Duramax Turbo-Diesel carry a 5-year/100,000-mile Powertrain Limited Warranty. GM notes that damage caused by improper maintenance may not be covered by the vehicle warranty.
This information is provided for general educational purposes only and does not constitute legal advice. Warranty coverage depends on the specific terms of your vehicle’s warranty agreement. Consult your owner’s manual or a qualified legal professional for guidance on your individual situation.
Schedule Duramax Service at Legacy GMC of Waxahachie
Our service department is at 1701 US-287 Byp in Waxahachie. Call our service team at (469) 553-0877, or book your visit online. For more upkeep guides, browse our service and parts tips and current service specials.
Disclaimers
The information in this article is general guidance and does not constitute a specific diagnostic or repair recommendation for any individual vehicle. Repair and maintenance decisions should be made in consultation with a certified technician based on the specific condition of your vehicle.
This information is provided for general educational purposes only and does not constitute legal advice. Warranty coverage depends on the specific terms of your vehicle’s warranty agreement. Consult your owner’s manual or a qualified legal professional for guidance on your individual situation.