2020 GMC Sierra 1500 Coolant Capacity & Type

The 2020 GMC Sierra 1500 coolant capacity varies by engine. This guide will provide detailed information on coolant capacity, type, flush intervals, and common cooling system issues.

Quick Answer

• Total Cooling System Capacity:
  • 2.7L L3B engine: Approximately 12.0 quarts (11.4 liters)
  • 5.3L L84/L82 engine: Approximately 16.0 quarts (15.1 liters)
  • 6.2L L87 engine: Approximately 16.0 quarts (15.1 liters)
  • 3.0L LM2 Duramax Diesel: Approximately 14.5 quarts (13.7 liters)
• OEM Coolant Spec: DEX-COOL, Orange/Red, Organic Acid Technology (OAT)
• Mix Ratio: 50/50 pre-mix or concentrate mixed with distilled water

Capacity by Engine Option

Flush Interval

For the 2020 GMC Sierra 1500, the recommended coolant flush interval is generally:

• Normal Duty: Every 5 years or 150,000 miles, whichever comes first.
• Severe Duty: If your driving conditions involve heavy towing, extreme temperatures, or frequent off-road use, it's advisable to inspect your coolant more frequently and consider a flush every 3 years or 50,000 miles.

How to Refill & Bleed

Properly refilling and bleeding the cooling system in your 2020 GMC Sierra 1500 is crucial to prevent air pockets that can lead to overheating. Always perform this procedure on a cool engine.

1. Drain the Old Coolant: With the engine cool, place a drain pan under the radiator. Open the radiator drain cock (petcock) on the bottom of the radiator. Some models may also have a drain on the engine block. Allow all coolant to drain.
2. Close Drain and Flush (Optional but Recommended): Close the drain cock. For a more thorough flush, you can use a radiator flush product according to its directions, or simply fill with distilled water, run the engine to operating temperature with the heater on high, let it cool, and drain again until the water runs clear.
3. Refill with New Coolant: Close all drain points. Slowly add the new 50/50 DEX-COOL coolant mixture to the radiator fill neck or the coolant reservoir until it reaches the 'COLD FILL' line. It is important to use distilled water if mixing concentrate.
4. Bleed the System:
   • Leave the radiator cap off (or reservoir cap off if filling through the reservoir).
   • Start the engine and let it run, with the heater on high, until it reaches operating temperature. As the thermostat opens, the coolant level may drop; add more coolant as needed to maintain the proper level.
   • Look for a bleeder screw near the thermostat housing or on a coolant hose. If present, slowly open the bleeder screw until a steady stream of coolant (without air bubbles) comes out, then close it.
   • Squeeze the upper and lower radiator hoses repeatedly to help dislodge air pockets.
   • Continue to monitor the coolant level and add as necessary until no more air bubbles appear in the radiator fill neck or reservoir.
   • Once the engine is at operating temperature and no more air is escaping, replace the radiator cap.
5. Final Check: Drive the vehicle and then re-check the coolant level when the engine is cool. Top off as needed.

Common Cooling System Issues

Owners of the 2020 GMC Sierra 1500, and the GM Silverado/Sierra platform of this generation, may encounter a few common cooling system issues:

• Water Pump Leaks: Water pump failures, often indicated by a coolant leak from the weep hole or a grinding noise, can occur. Regular inspection of the water pump for leaks and unusual noises is recommended.
• Thermostat Failures: A stuck open thermostat can lead to the engine running too cool, reducing efficiency, while a stuck closed thermostat will cause overheating. Symptoms include erratic temperature gauge readings or the engine not reaching operating temperature.
• Coolant Expansion Tank Leaks/Cracks: The plastic coolant expansion tank can develop hairline cracks over time, leading to slow coolant leaks and a decreasing coolant level.
• Radiator Leaks: Road debris or age can lead to perforations in the radiator, causing coolant leaks. Visible leaks, particularly at the seams or fins, indicate a problem.
• Hose Leaks: Coolant hoses can degrade over time, leading to cracks, bulges, or leaks at connection points. Regular inspection of hoses for softness, hardness, or visible damage is important.

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