2021 GMC Sierra 3500HD maintenance schedule

The 2021 Sierra 3500HD is part of the GMT T1XX generation (2020-2026), sold as a pickup. Below: its service intervals with the source behind each one, the fluids it takes, and the NHTSA recalls issued for it.

Service schedule

What the 2021 Sierra 3500HD needs, and when

1 of these 12 items comes from GMC's own published schedule. Manufacturer rows link to GMC's own schedule, Independent rows to a service shop or parts retailer's published guide.

ServiceIntervalSource
Engine oil and filter

Check OLM indicator

7,500 mi / 1 yearIndependent
Engine air filter

Diesel may require earlier replacement; 45,000 mi is a check cadence, not a confirmed replacement interval

Inspect, replace as neededIndependent
Cabin air filter

Replace more frequently in dusty environments

22,500 mi / 2 yearsIndependent
Tire rotation

Check tread wear and balance

7,500 mi / 1 yearIndependent
Brake fluid60,000 mi / 5 yearsIndependent
Engine coolant

DEX-COOL drain and replenish

150,000 mi / 5 yearsIndependent
Transmission fluid

Severe duty towing interval

45,000 miIndependent
Spark plugs (Gas)97,500 miIndependent
Serpentine belt

Inspect accessory drive belts

150,000 mi / 10 yearsIndependent
Differential and transfer case fluid

For 4WD models

45,000 miIndependent
PCV valve (Gas)Inspect, replace as neededManufacturer
12V battery

Test cold-cranking amps annually

Inspect, replace as neededIndependent

Intervals are for normal driving; towing, short trips, extreme heat or dust shorten them. Services we could not find an interval for are left off rather than guessed.

Fluids and engines

What goes in it

Engine oil
5W-30 / 15W-40
Coolant
DEX-COOL
Transmission fluid
DEXRON ULV

Powertrains in this generation

  • 6.6L 8-cyl (L8T), 401 hp, 6-Speed/10-Speed, RWD/4WD
  • 6.6L 8-cyl diesel (L5P), 445 hp, 10-Speed Allison, RWD/4WD

Confirm the exact spec against the owner's manual or the label under the hood; capacities vary by engine and drivetrain.

Safety recalls

5 NHTSA recalls for the 2021 GMC Sierra 3500HD

From NHTSA's recall database, matched by model and year. Recall repairs are free at GMC dealers, and a given car may already be fixed or fall outside a campaign, so check the VIN at nhtsa.gov/recalls before you buy.

Power train

NHTSA 24V797000

October 2024

General Motors, LLC (GM) is recalling certain 2020-2022 Chevrolet Silverado 1500, 2500, 3500, GMC Sierra 1500, 2500, 3500, 2021 Cadillac Escalade, Escalade ESV, Chevrolet Tahoe, Suburban, GMC Yukon, and Yukon XL vehicles equipped with diesel engines. The transmission control valve may fail and cause the rear wheels to lock-up.

Remedy: Dealers will install new transmission control module software, free of charge. GM will provide a special coverage program to cover the repair of transmissions that are identified by the remedy software as containing a defective control valve. Owner notification letters were mailed December 12, 2024. Owners may contact GM customer service at 1-888-988-7267, Cadillac customer service at 1-800-458-8006, GMC customer service at GMC 1-800-462-8782 or Chevrolet customer service at 1-800-222-1020. GM's number for this recall is N242454440.

Latches/locks/linkages

NHTSA 24V060000

February 2024

General Motors, LLC (GM) is recalling certain 2020-2024 Chevrolet Silverado 2500, 3500, GMC Sierra 2500 and 3500 vehicles equipped with power-unlatching tailgates. The tailgate's electronic gate-release switch may short circuit due to water intrusion, which can result in the tailgate inadvertently unlatching while the vehicle is in park.

Remedy: Owners are advised to check that the tailgate is closed and latched before driving. Dealers will replace the exterior touchpad switch assemblies, free of charge. Owner notification letters were mailed May 17, 2024. Owners may contact Chevrolet customer service at 1-800-222-1020 or GMC customer service at 1-800-462-8782. GM's number for this recall is N232426400.

Service brakes, hydraulic

NHTSA 21V758000

September 2021

General Motors, LLC (GM) is recalling certain 2021-2022 Chevrolet Silverado 2500, Silverado 3500, GMC Sierra 2500, and Sierra 3500 vehicles with electronic brake control modules (EBCM) replaced during vehicle assembly. The bolts that attach the brake pressure modulator valve (BPMV) assembly may not be properly tightened, which could fail to seal the two sub-assemblies and allow water intrusion.

Remedy: Owners are advised to park outside and away from other structures until the recall repair is completed. Dealers will replace the BPMV assembly, free of charge. Owner notification letters were mailed on October 20, 2021. Owners may contact Chevrolet customer service at 1-800-222-1020 or GMC customer service at 1-800-462-8782. GM's number for this recall is N212349181.

Seat belts

NHTSA 20V811000

December 2020

General Motors, LLC (GM) is recalling certain 2020 Chevrolet Bolt EV and 2021 GMC Canyon and Sierra 1500, 2500 and 3500, Yukon, Yukon XL, Cadillac Escalade and Escalade ESV and Chevrolet Blazer, Camaro, Colorado, Equinox, Silverado 1500, 2500 and 3500, Suburban and Tahoe vehicles. Incorrect bolts may have been used at one or more fastening locations to secure the seat belts to the vehicle. If an incorrect bolt was used, the seat belt may not be properly attached to the vehicle.

Remedy: GM will notify owners, and dealers will replace the suspect bolts, free of charge. The recall began January 29, 2021. Owners may contact GMC customer service at 1-800-462-8785, Cadillac customer service at 1-800-458-8006, or Chevrolet customer service at 1-800-222-1020. GM's number for this recall is N202322230.

Seat belts

NHTSA 20V792000

December 2020

General Motors, LLC (GM) is recalling certain 2019-2021 Chevrolet Silverado 1500 and GMC Sierra 1500, 2021 Chevrolet Suburban and Tahoe and GMC Yukon XL and 2020-2021 Chevrolet Silverado 2500 and 3500 and GMC Sierra 2500 and 3500 vehicles. The seat belt brackets may not be secured to the seat frame in the front-row center seating position.

Remedy: GM will notify owners, and dealers will inspect left-side and right-side front-row center seat-belt bracket attachments and reassemble it correctly as necessary, free of charge. The recall began January 26, 2021. Owners may contact GMC customer service at 1-800-462-8782, Chevrolet customer service at 1-800-222-1020. GM's number for this recall is N202314670.

Running costs

What maintenance typically costs

A typical year of maintenance
$912
Five years of maintenance
$4,560
The major service near 100,000 mi
$1,500

Typical US independent-shop estimates for this generation; they vary by region and condition.

Other Sierra 3500HD model years

GMT T1XX (2020-2026)

GMT K2XX (2015-2019)

GMT900 (2014-2014)

Shopping new? The GMC Sierra 3500HD guide covers the current model, with what it costs to keep for 1 to 15 years.

Sources

Researched 2026-09-19. Modeling, not mechanic advice - always confirm against your car's owner's manual and service records.

Running a Sierra 3500HD for income?

Carlyle scores the exact listing on cost per remaining mile and projected Turo income, so you know what a 2021 Sierra 3500HD earns before you buy it.

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