The 2021 GMC Sierra 1500 with the 3.0L Duramax diesel uses a 24-gallon fuel tank (approximately 91 liters).
This article provides the official capacity, what it means for range, and notes on configuration differences that buyers should consider when evaluating a specific truck.
Official fuel tank capacity
GM lists the standard fuel tank capacity for the 2021 Sierra 1500 with the 3.0L Duramax at 24 gallons. This figure is typical across most crew cab configurations; verify your exact build sheet for any variation.
- Fuel tank capacity: 24 gallons (91 L)
In practice, the commonly cited capacity for 2021 Duramax Sierra 1500 models is 24 gallons, though some configurations or dealer-specific options could affect measurements.
What 24 gallons means for range
Range depends on driving conditions and efficiency. The 3.0 Duramax diesel is known for strong highway fuel economy, which helps maximize the distance you can cover on a full tank. Real-world mileage will vary based on speed, payload, terrain, and climate control usage.
Considerations by configuration
Most Sierra 1500 configurations that pair with the 3.0L Duramax share the same 24-gallon tank. If you are evaluating a specific truck, confirm the exact capacity for that VIN via the window sticker or GM’s official documentation to account for any rare deviations or optional equipment.
Why tank size matters for buyers
Understanding the tank size aids in trip planning, fuel budgeting, and maintenance scheduling, especially for long drives or work routes where fuel stops are a consideration.
Verification and sources
Official specifications come from General Motors’ published materials for the 2021 Sierra 1500 with the 3.0L Duramax. For precise numbers on a particular vehicle, consult the original window sticker (Monroney label) or GM’s product information for that model year.
Summary
The 2021 GMC Sierra 1500 with the 3.0 Duramax diesel is equipped with a 24-gallon fuel tank, equating to about 91 liters. This capacity is standard across most configurations, providing a practical driving range aligned with the diesel’s efficiency. Always confirm the exact tank size for your specific truck through official documentation or a dealership.
How big is the DEF tank on a 2021 GMC Sierra 3.0 diesel?
5.4 gallons
According to GM specifications, the DEF tank capacity for vehicles equipped with the Duramax 3.0L LZ0 engine is 20.5 liters, or 5.4 gallons. Filling the DEF tank is straightforward – first, locate the blue DEF cap behind the combined fuel/DEF door. Turn the DEF cap counterclockwise to remove it, and pour in the DEF.
How big is the fuel tank on a 2021 GMC Sierra 1500 3.0 diesel?
Approximately 24 gallons
The standard fuel tank sizes for the 3.0L Duramax-powered Sierra 1500 vary based on cab configuration: Crew Cab & Double Cab: Approximately 24 gallons.
How many miles per gallon does a 2026 1500 gmc get with a 3.0 L Duramax turbo-diesel engine?
– 3.0L Duramax Turbo-Diesel: Up to ~23 city / 29 highway mpg, this engine sets the bar high for the best gas economy truck, making it a clear winner for those who prioritize miles on the road!
How many miles per gallon does a GMC Sierra 1500 3.0 Duramax get?
23 mpg city / 29 mpg highway
3.0L Duramax Turbo-Diesel Six-Cylinder Engine (2WD): 23 mpg city / 29 mpg highway / 25 mpg combined.