2019 GMC Sierra 1500 Coolant Capacity, Type, and Flush Guide

The 2019 GMC Sierra 1500 holds between 11.8 and 18.2 quarts (11.2 to 17.2 liters) of coolant, depending on the engine option and towing package installed. As an ASE-certified master technician, I frequently service the T1XX generation Sierra, and knowing the exact fluid specifications is critical to keeping your truck's engine running at the optimal temperature and preventing costly internal corrosion.

Quick answer

• Total cooling system capacity: 11.8 – 18.2 quarts (11.2 – 17.2 liters) depending on the engine.
• OEM coolant spec: ACDelco Dex-Cool (Orange). This is an OAT (Organic Acid Technology) coolant meeting GM specification GMW3420.
• Mix ratio: 50/50 mixture of Dex-Cool concentrate and clean, drinkable water (deionized or distilled water is highly preferred) or a pre-mixed 50/50 Dex-Cool solution.

Capacity by engine option

The 2019 Sierra 1500 was completely redesigned and offered with several different powertrains. If your truck is equipped with the Max Trailering Package, it features a higher capacity radiator.

Note: Always verify your specific capacity in your owner's manual or underhood emission label, as RPO codes can slightly alter these amounts.

Flush interval

GM's Dex-Cool is designed to be a long-life coolant, but it still requires regular maintenance.

• Normal Duty: General Motors recommends draining, flushing, and refilling the cooling system every 150,000 miles or 5 years, whichever comes first.
• Severe Duty: If you frequently tow heavy loads, idle for extended periods, or drive in extreme heat or dusty conditions, you should inspect the coolant condition annually. Many technicians recommend dropping the interval to every 100,000 miles or 5 years to ensure the anti-corrosion additives in the OAT chemistry remain fully effective.

How to refill & bleed

Modern GM trucks utilize a pressurized surge tank rather than a traditional radiator cap, which can make bleeding the system a bit tricky.

1. Drain the system: Wait until the engine is completely cold. Open the radiator petcock (if equipped) or remove the lower radiator hose to drain the old coolant.
2. Vacuum fill (Highly Recommended): The best and fastest way to refill a 2019 Sierra is by using a pneumatic vacuum coolant refill tool attached to the surge tank. This draws a vacuum on the entire system and pulls the new coolant in without introducing any air pockets. Air trapped in the 2.7L turbo or the V8 blocks can cause severe localized overheating.
3. Manual bleed (Alternative): If you don't have a vacuum filler, slowly pour the 50/50 mixture into the surge tank until it reaches the "Cold Fill" line.
4. Burp the system: Leave the surge tank cap off. Start the engine and turn the cabin heater to its maximum temperature setting with the fan on low. Let the truck idle until the engine reaches operating temperature and the thermostat opens (the upper radiator hose will get hot).
5. Top off: As the system burps out trapped air, the coolant level in the surge tank will drop. Top it off to the "Cold Fill" line and install the cap tightly. Test drive and recheck the level the next morning when cold.

Common cooling system issues

For the 2019 GMC Sierra 1500, there are a few specific cooling system quirks to watch out for:

• Water pump weep hole leaks: On the 5.3L and 6.2L V8s, the mechanical water pump is known to occasionally develop a slow leak from the weep hole as the internal seal wears out. Check for an orange crust around the water pump pulley.
• Radiator end tank failures: The plastic side tanks on the radiator undergo intense thermal cycling. Over time, micro-cracks can form where the plastic is crimped to the aluminum core, leading to slow coolant loss.
• Thermostat housing leaks: The gasket mating the thermostat housing to the engine block can degrade, causing a minor drip.

If you're unsure about tackling a coolant flush or suspect your truck has a leak, don't risk overheating your engine. Find a trusted shop on Repairius.