2025 Chevrolet Silverado 2500HD Fluid Type, Spec, and Capacity Reference

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil (6.6L Gas L8T)	SAE 0W-30 dexosD	8.0 quarts / 7.6 liters
Engine Oil (6.6L Duramax L5P)	SAE 5W-40 or 15W-40 API CK-4 / dexos2	10.0 quarts / 9.5 liters
Engine Coolant	DEX-COOL OAT (Orange)	15.6 - 16.9 quarts / 14.8 - 15.9 liters (Verify)
Automatic Transmission Fluid	DEXRON ULV	~11.0 quarts / 10.4 liters (Service Fill)
Transfer Case Fluid	DEXRON VI	~1.6 quarts / 1.5 liters
Front Differential Fluid	SAE 75W-90 Synthetic Gear Oil	~1.8 quarts / 1.7 liters
Rear Differential Fluid	SAE 75W-90 Synthetic Gear Oil	~3.2 quarts / 3.0 liters
Brake Fluid	DOT 3	As required
Power Steering Fluid	DEXRON VI	As required
Windshield Washer Fluid	Good Quality Washer Solvent	~4.7 quarts / 4.5 liters
Diesel Exhaust Fluid (DEF)	API Certified (ISO 22241)	~7.3 gallons / 27.6 liters

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Engine Oil

Maintaining the correct engine oil is the single most important aspect of truck longevity. The 2025 Silverado HD offers two distinct engines, each with its own specific oil requirement. Do not interchange them.

• 6.6L V8 L8T (Gasoline): This engine requires SAE 0W-30 oil meeting the GM dexosD specification. The use of dexosD is critical for ensuring proper lubrication, fuel economy, and emissions system performance. Using other viscosities or specifications can lead to internal engine damage.
• 6.6L V8 L5P Duramax (Diesel): The diesel engine requires SAE 5W-40 synthetic diesel engine oil that meets API Service CK-4 standards. In climates that do not see temperatures below 0°F (-18°C), SAE 15W-40 is also acceptable. Look for oils that are also certified for GM dexos2. Using the correct oil is paramount for the health of the turbocharger and the complex emissions system, including the Diesel Particulate Filter (DPF).

Intervals: Always follow the truck's onboard Oil Life Monitor (OLM) system. However, for trucks under severe service (heavy towing, frequent idling, dusty conditions), a 5,000-mile interval is a safe benchmark. Never exceed one year between changes, regardless of mileage.

Engine Coolant

The 2025 Silverado HD uses GM DEX-COOL coolant from the factory. This is an Organic Acid Technology (OAT) coolant, easily identified by its signature orange color.

• Specification: Use a silicate-free, phosphate-free OAT coolant meeting GM specification GMW3420.
• Common Pitfall: Never mix DEX-COOL with other coolant types, such as conventional green Inorganic Acid Technology (IAT) or Hybrid OAT (HOAT) coolants found in other vehicles. Mixing chemistries can cause the coolant to gel, leading to blockages, overheating, and significant damage to the radiator, water pump, and heater core.

Intervals: DEX-COOL is a long-life coolant, typically rated for 5 years or 150,000 miles. However, it's wise to inspect the coolant level and condition at every oil change.

Automatic Transmission Fluid

All 2025 Silverado 2500HD models are equipped with an Allison 10-speed automatic transmission. This advanced transmission requires a very specific, low-viscosity fluid to operate correctly.

• Specification: Use DEXRON ULV (Ultra Low Viscosity) automatic transmission fluid. The GM part number is 19417577.
• Common Pitfall: Do not use DEXRON VI, DEXRON III, or any "universal" ATF. Using the wrong fluid will cause poor shifting, torque converter shudder, and can quickly lead to catastrophic transmission failure. This is not a place to compromise; use only the specified ULV fluid.

Intervals: Under normal service, the transmission fluid and filter should be changed every 45,000 miles. For severe service, consult the owner's manual, but consider a more frequent interval.

Driveline Fluids (4WD)

Transfer Case: The transfer case directs power to the front and rear axles in 4WD models.

• Specification: It requires DEXRON VI (the previous-generation automatic transmission fluid). Do not confuse this with the ULV fluid used in the transmission itself.

Front and Rear Differentials: The differentials transfer power to the wheels.

• Specification: Both front and rear differentials call for SAE 75W-90 Synthetic Axle Lubricant meeting GM specification 9986115.
• Limited-Slip Additive: The factory fluid is formulated for use in axles with or without the G80 locking rear differential, so no additional limited-slip friction modifier is required when using the OEM-spec fluid.

Brake & Power Steering Fluid

Brake Fluid: The hydraulic brake system requires DOT 3 motor vehicle brake fluid. While DOT 4 fluid has a higher boiling point and is compatible, it is also more hygroscopic (absorbs moisture faster). Stick with a high-quality DOT 3 fluid from a sealed container for best results. The fluid should be changed every 2-3 years, as moisture contamination can compromise braking performance.

Power Steering Fluid: The hydraulic power steering system in the Silverado HD also uses automatic transmission fluid.

• Specification: Use DEXRON VI ATF.

Washer & Diesel Exhaust Fluid

Windshield Washer Fluid: Use any good quality, commercial windshield washer solvent. In winter months, be sure to use a fluid with an adequate freeze protection rating for your climate.

Diesel Exhaust Fluid (DEF): For Duramax diesel models, maintaining the DEF tank is critical for the vehicle to run. The system injects DEF into the exhaust stream to reduce NOx emissions.

• Specification: Use a high-quality Diesel Exhaust Fluid that is API Certified and meets the ISO 22241 standard. This will be clearly marked on the container.
• Common Pitfall: Never put anything other than fresh, clean DEF into the DEF tank. Contamination with fuel, dirt, or even water can destroy the very expensive SCR (Selective Catalytic Reduction) system components. The DEF filler neck is located next to the fuel filler and is clearly marked with a blue cap.

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