2023 GMC Sierra 1500 Coolant Capacity & Type Guide

The 2023 GMC Sierra 1500 holds between 11.5 and 17.4 quarts of coolant, depending on which engine and towing package your truck is equipped with. As an ASE-certified master technician, I regularly service these modern GM trucks, and using the exact factory-specified coolant is absolutely critical to maintaining the longevity of the engine and the complex thermal management systems onboard.

Here is everything you need to know about the coolant capacity, type, and servicing procedures for the 2023 GMC Sierra 1500.

Quick answer

• Total Cooling System Capacity: 11.5 to 17.4 quarts (10.9 to 16.5 liters), dependent on engine option and factory tow packages.
• OEM Coolant Spec: AC Delco Dex-Cool. This is an OAT (Organic Acid Technology) coolant, traditionally orange in color, meeting GM specification GMW3420 (formerly GM 6277M).
• Mix Ratio: 50/50 mixture of Dex-Cool concentrate and clean, drinkable water (preferably distilled or deionized water to prevent scale buildup). You can also purchase pre-mixed 50/50 Dex-Cool.

Capacity by engine option

The 2023 Sierra 1500 is offered with four distinct powertrains. Keep in mind that trucks equipped with heavy-duty cooling packages (Max Trailering Package) may hold slightly more coolant than the base figures. Always fill to the "Cold Full" line on the surge tank rather than just blindly pouring in a specific volume.

Note: The 3.0L Duramax and the 2.7L Turbo utilize complex secondary cooling loops for charge air cooling and thermal management. The capacities listed above reflect the primary engine cooling system.

Flush interval

GM's Dex-Cool is designed as an extended-life coolant, but it is not a lifetime fluid. Over time, the anti-corrosion additives break down.

• Normal Duty: GM recommends flushing the cooling system every 5 years or 150,000 miles, whichever comes first.
• Severe Duty: If you frequently tow heavy trailers, idle for long periods, or drive in extreme heat or dusty conditions, I strongly recommend inspecting the coolant condition at 50,000 miles and performing a complete system flush every 3 years or 100,000 miles. Leaving degraded Dex-Cool in the system for too long is a notorious cause of gasket failures and heater core clogging.

How to refill & bleed

Modern GM trucks are notorious for trapping air pockets in the cooling system, which can lead to localized overheating and erratic heater performance.

1. Prep the vehicle: Ensure the engine is completely cold. Place a large drain pan under the radiator drain petcock (usually located on the lower driver or passenger side of the radiator).
2. Drain the system: Open the surge tank cap to break the vacuum, then open the radiator petcock to drain the old fluid. Close the petcock securely once drained.
3. Use a Vacuum Fill Tool: For the 2023 Sierra, a vacuum coolant refill tool (like an Airlift) is highly recommended. Hook the tool up to the surge tank, draw a vacuum on the entire cooling system, and allow the vacuum to pull the new 50/50 Dex-Cool mixture into the engine. This virtually eliminates trapped air.
4. Manual Bleed (If vacuum tool is unavailable): Slowly pour the 50/50 mix into the surge tank until it reaches the cold fill line. Start the engine and turn the cabin heater to its maximum setting. Let the engine idle and warm up until the thermostat opens (you will feel the upper radiator hose get hot).
5. Top off: As the thermostat opens and the system burps air, the fluid level in the surge tank will drop. Slowly add coolant to keep it at the cold fill line. Reinstall the cap tightly and take a test drive. Recheck the cold level the next morning.

Common cooling system issues

While the 2023 Sierra 1500 is relatively new, this generation of GM trucks has a few known cooling system quirks to watch out for as the miles add up:

• Coolant Control Valve (3.0L Duramax): The diesel engines use a complex rotary control valve to manage coolant flow to the block, heater core, and transmission. These valves can occasionally stick, leading to check engine lights or erratic temperature gauge readings.
• Water Pump Weepage: The V8 models (5.3L and 6.2L) have a history of slow weeping from the water pump weep hole as they approach 70,000+ miles. Keep an eye out for a crusty orange residue around the front of the engine block.
• Radiator End Tank Leaks: The crimped plastic end tanks on the radiator can begin to seep coolant after years of thermal cycling, especially on trucks that tow heavily.

Don't ignore a low coolant warning or a rising temperature gauge. Find a trusted shop on Repairius.