2020 Chevrolet Silverado 3500HD Coolant Capacity & Type

The 2020 Chevrolet Silverado 3500HD coolant capacity varies depending on the engine, generally holding between 24.5 to 29.5 quarts (23.2 to 27.9 liters) of coolant.

Quick Answer

• Total Cooling System Capacity:
  • 6.6L V8 L8T (Gasoline): Approximately 24.5 quarts (23.2 liters)
  • 6.6L V8 L5P Duramax (Diesel): Approximately 29.5 quarts (27.9 liters)
• OEM Coolant Spec: DEX-COOL extended life coolant (Orange, OAT - Organic Acid Technology), meeting GM Standard GMW3420.
• Mix Ratio: 50/50 pre-mix, or 50% concentrate with 50% distilled water.

Capacity by Engine Option

Flush Interval

For a 2020 Chevrolet Silverado 3500HD, the recommended coolant flush interval depends on usage:

• Normal Duty: Replace DEX-COOL coolant every 5 years or 150,000 miles, whichever comes first.
• Severe Duty: If you frequently tow heavy loads, drive in extreme temperatures, or operate under dusty conditions, it's advisable to inspect your coolant more frequently and consider replacing it closer to 3 years or 45,000 miles, or as indicated by a coolant test.

How to Refill & Bleed

Refilling and bleeding the cooling system on your 2020 Chevrolet Silverado 3500HD is crucial to prevent air pockets, which can lead to overheating. Always perform this procedure on a cool engine.

1. Drain Old Coolant: With the engine cool, place a drain pan under the radiator. Open the radiator drain cock and remove the radiator cap to allow the system to drain completely. For a more thorough drain, you might also need to open drain plugs on the engine block if present (consult your service manual).
2. Close Drain and Refill: Once drained, close the radiator drain cock. Begin refilling the system with the specified DEX-COOL 50/50 mix through the radiator fill neck or the coolant reservoir.
3. Bleed Air - Gasoline (6.6L L8T): For the gasoline engine, often the system will self-bleed to a good extent. Fill the reservoir to the "cold fill" line. Start the engine with the heater on full blast (lowest fan speed) and the radiator cap off. Allow the engine to reach operating temperature. As the thermostat opens and coolant circulates, air will be purged. You may need to gently squeeze the upper radiator hose to help dislodge air bubbles. Top off the coolant level as needed. Secure the radiator cap once no more bubbles appear.
4. Bleed Air - Diesel (6.6L L5P Duramax): The Duramax engine has a more intricate cooling system and may benefit from a vacuum fill tool for optimal air removal. If not using a vacuum tool, follow the general guidelines for the gasoline engine, but pay extra attention to ensuring all air is purged. Some Duramax engines may have specific bleed screws; consult your vehicle's service manual for their locations and proper procedure. Continue to monitor the coolant level in the reservoir over the next few drive cycles, topping off as necessary.
5. Final Check: After the engine has cooled, recheck the coolant level in the reservoir and top off if necessary. Inspect for any leaks.

Common Cooling System Issues

For the 2020 Chevrolet Silverado 3500HD, common cooling system issues for this generation can include:

• Coolant Leaks: Leaks can occur from hoses, the radiator, water pump, or thermostat housing. The orange DEX-COOL can sometimes leave a noticeable residue when it dries.
• Water Pump Failure: While not exclusive to this model year, water pump failures can occur, leading to coolant leaks or overheating.
• Thermostat Issues: A faulty thermostat can cause the engine to run too hot (stuck closed) or too cold (stuck open), impacting efficiency and potentially causing damage.
• Radiator Cap Problems: A failing radiator cap can lead to improper system pressure, resulting in coolant loss or inefficient cooling.
• Heater Core Clogs: Especially in vehicles with higher mileage or neglected coolant maintenance, heater cores can become partially or fully clogged, leading to poor cabin heating. This is often exacerbated by mixing incompatible coolants.
• Diesel Specific Concerns (6.6L L5P Duramax): The Duramax engine's cooling system is robust but requires proper maintenance. Issues like EGT (Exhaust Gas Temperature) sensor failures can indirectly affect cooling system performance by altering engine operation. Maintaining the correct coolant type and level is paramount for the longevity of the turbocharger and other critical components.

Proper and timely maintenance, including using the correct DEX-COOL coolant, is essential for the longevity and reliability of your 2020 Chevrolet Silverado 3500HD's cooling system.

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