2025 GMC Yukon Coolant Capacity, Type, and Maintenance Guide

The 2025 GMC Yukon holds between 14.5 and 18.5 quarts (13.7 to 17.5 liters) of coolant, depending on your specific engine option and whether the vehicle is equipped with a rear passenger heating system or a heavy-duty towing package. As an ASE-certified master technician, I regularly service the GM T1XX platform, and knowing the exact specifications for your cooling system is critical to keeping these large SUVs on the road and out of the repair bay.

Quick answer

• Total cooling system capacity: 14.5 to 18.5 quarts (13.7 – 17.5 liters), varying by engine and climate control options.
• OEM coolant spec: ACDelco DEX-COOL. This is an Orange, Organic Acid Technology (OAT) coolant that meets the General Motors GMW3420 specification.
• Mix ratio: A 50/50 mixture of DEX-COOL concentrate and clean, drinkable (preferably distilled or deionized) water. You can also purchase pre-mixed 50/50 DEX-COOL. In extremely cold climates (below -30°F), a 60/40 coolant-to-water ratio may be used, but never exceed 70% coolant.

Capacity by engine option

The 2025 GMC Yukon offers three primary engine choices. Keep in mind that models equipped with rear climate control systems (rear heater core) or the Max Trailering Package will fall on the higher end of these capacity ranges due to the extra lines and auxiliary coolers.

*Note: The 3.0L Duramax diesel features multiple independent cooling circuits, including a separate loop for the charge air cooler (CAC). The capacities listed are for the primary engine cooling system.

Flush interval

For the 2025 GMC Yukon, General Motors recommends replacing the engine coolant every 150,000 miles or 5 years, whichever comes first, under normal driving conditions.

However, if you subject your Yukon to severe duty—which includes frequent towing, extensive idling, driving in heavy stop-and-go traffic, or operating in extremely dusty or mountainous environments—you should inspect the coolant strength and level annually and plan to flush the system closer to the 100,000-mile mark. DEX-COOL is formulated for long life, but its anti-corrosion inhibitors eventually degrade, which can lead to heater core clogging and water pump failure.

How to refill & bleed

Modern GM cooling systems, particularly on the V8 and Duramax engines, are notorious for trapping air. A vacuum-fill tool is highly recommended for the 2025 Yukon.

1. Drain the system: With the engine cold, open the radiator drain petcock. Dispose of the old coolant at an approved recycling facility.
2. Pull a vacuum (Preferred Method): Attach a pneumatic cooling system vacuum tool to the surge tank. Draw the system down to roughly 20-25 inHg. This verifies the system has no leaks and removes all air.
3. Draw in the new coolant: Open the valve on your vacuum tool to draw the 50/50 DEX-COOL mixture directly into the system until the gauge drops to zero.
4. Manual bleed (Alternative): If you don't have a vacuum tool, slowly fill the surge tank to the "Cold Fill" line. Leave the cap off. Start the engine and turn the cabin heater to maximum heat and fan speed.
5. Warm up and top off: Let the engine idle until the upper radiator hose gets hot (indicating the thermostat has opened). You will see the coolant level drop as air burps out. Top off the surge tank to the cold fill line, install the cap tightly, and test drive. Re-check the level the next morning when the engine is completely cold.

Common cooling system issues

While the 2025 Yukon is a robust vehicle, this generation of GM trucks and SUVs shares a few common cooling system characteristics to watch out for:

• Water Pump Weepage: The mechanical water pumps on the 5.3L and 6.2L V8 engines are known to develop a slow weep from the weep hole as the internal seal wears. If you smell sweet coolant but don't see a puddle, check the bottom of the water pump pulley.
• Thermostat Sticking: Electronic thermostat housings can occasionally stick open, leading to a Check Engine Light (often code P0128 - Coolant Thermostat Below Regulating Temperature).
• Radiator End Tank Leaks: Over time, the crimp seals where the plastic side tanks meet the aluminum radiator core can separate due to thermal cycling and chassis flex, causing slow leaks.

If you suspect a leak or need a professional coolant flush, don't ignore it. Overheating can cause catastrophic engine damage. Find a trusted shop on Repairius.