2018 GMC Yukon Coolant Capacity & Type

Your 2018 GMC Yukon's cooling system holds between 10.8 and 14.5 quarts (10.2 and 13.7 liters) of coolant, depending on the engine and radiator option.

Quick Answer

• Total Cooling System Capacity: 10.8 to 14.5 quarts (10.2 to 13.7 liters)
• OEM Coolant Specification: GM DEX-COOL® (Orange, Organic Acid Technology - OAT)
• Manufacturer Spec Number: GM 6277M
• Mix Ratio: 50/50 mix of DEX-COOL® concentrate and deionized water. Pre-mixed formulations are recommended.

Capacity by Engine Option

The 2018 GMC Yukon was available with two different V8 engines. The total cooling system capacity varies slightly based on the engine and which radiator is installed (standard vs. heavy-duty).

Note: These capacities include the engine, radiator, and heater core. A simple drain and refill will typically replace about half of the total system volume.

Flush Interval

Following the proper service interval is critical for preventing corrosion and ensuring the long life of your cooling system components.

• Normal Service: General Motors recommends a coolant flush every 5 years or 150,000 miles, whichever comes first.
• Severe Duty: If the vehicle is used for frequent towing, idling in heavy traffic, or driven in extreme temperatures, it is advisable to shorten this interval. Many technicians recommend a flush every 60,000 to 100,000 miles under these conditions.

How to Refill & Bleed

Properly refilling and bleeding the air from the cooling system is essential to prevent overheating. While these trucks do not have a traditional bleeder screw, air can still be purged effectively.

1. Mix Coolant: If using concentrate, mix a 50/50 solution of DEX-COOL® and deionized water in a clean container.
2. Slow Fill: With the engine off and cool, slowly pour the new coolant into the coolant reservoir/degas bottle. Do not fill the radiator directly. Fill until the level reaches the "Full Cold" mark.
3. Warm Up: Leave the reservoir cap off and start the engine. Turn the heater on to its highest temperature setting and the fan to a low speed. This allows coolant to circulate through the heater core.
4. Purge Air: As the engine warms up to operating temperature (the upper radiator hose will become hot), you will see the coolant level in the reservoir drop as air is purged from the system. Bubbles may also appear.
5. Top Off: Continue to add coolant to the reservoir to maintain the "Full Cold" level as the air escapes. Once the engine reaches full temperature and the thermostat opens, the level should stabilize.
6. Final Check: Replace the reservoir cap and check for leaks. Monitor the coolant level for the next few drives, topping off as needed only when the engine is cool.

Pro Tip: For a faster, more effective air purge, technicians often use a vacuum-fill tool. This device pulls the entire cooling system into a deep vacuum and uses that vacuum to draw fresh coolant in, eliminating the possibility of air pockets.

Common Cooling System Issues

This generation of GMC Yukon (2015-2020) is generally reliable, but some cooling system issues are known to occur:

• Water Pump Failure: A weep hole on the water pump will leak coolant when the internal seal begins to fail. This is often the first sign that replacement is needed.
• Thermostat Issues: A thermostat stuck open will cause the engine to warm up very slowly and may trigger a check engine light (P0128). A thermostat stuck closed will cause rapid overheating.
• Radiator Leaks: Leaks can develop at the seams where the plastic side tanks are crimped to the aluminum core. This often appears as a crusty orange or pink residue.
• Heater Core Clogging: Though less common, using the wrong type of coolant or not flushing the system on schedule can lead to debris clogging the narrow passages of the heater core, resulting in poor cabin heat.

Keeping your cooling system full of the correct DEX-COOL® coolant and flushing it at the recommended interval is the best way to prevent these common problems.

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