2025 Jeep Gladiator Coolant Capacity, Type, and Service Guide

The 2025 Jeep Gladiator holds approximately 13.4 quarts (12.7 liters) of coolant in its standard 3.6L Pentastar V6 cooling system. As an ASE-certified master technician, I regularly see these rugged midsize trucks in the shop, and knowing exactly what type of coolant to use and how much is required is critical to keeping the engine from overheating on the trail or the highway. Because the Gladiator shares its architecture with the Wrangler, its cooling system is built for heavy duty, but it absolutely demands the correct fluids and maintenance procedures to stay reliable.

Quick Answer

If you are topping off or completely refilling your 2025 Jeep Gladiator, here are the vital statistics you need to know:

• Total Cooling System Capacity: Approximately 13.4 quarts (12.7 liters) for the 3.6L V6 engine.
• OEM Coolant Specification: Mopar 10 Year/150,000 Mile Formula OAT (Organic Additive Technology). The specific manufacturer standard is MS-12106. The factory coolant is Purple in color.
• Mix Ratio: A 50/50 mixture of OAT coolant concentrate and distilled water, or a pre-mixed 50/50 solution. Never use tap water, as the minerals will cause scaling inside the radiator and engine block.

Warning: Never mix the purple Mopar OAT (MS-12106) with the older orange Mopar HOAT (MS-9769) or any traditional green IAT coolant. Mixing different coolant chemistries can cause the fluid to gel, leading to catastrophic engine overheating and plugged heater cores.

Capacity by Engine Option

For the 2025 model year, Jeep has streamlined the Gladiator's powertrain lineup. The EcoDiesel has been discontinued, leaving the proven 3.6L Pentastar V6 as the standard powerplant.

Note: Capacities are approximate. If you are doing a standard drain and fill without flushing the block or heater core, you will likely only need about 2 to 2.5 gallons (8-10 quarts) of 50/50 mix to refill the system.

Flush Interval

Chrysler/Jeep states that the Mopar OAT coolant has a lifespan of 10 years or 150,000 miles under normal driving conditions. However, from a technician's perspective, you should tailor this to your actual usage:

• Normal Duty: Flush and replace the coolant every 10 years or 150,000 miles.
• Severe Duty: If you frequently tow, off-road in extreme heat, idle for long periods, or drive in heavy stop-and-go traffic, I recommend reducing this interval to every 5 years or 100,000 miles. Regularly check the coolant reservoir; if the fluid looks cloudy or has suspended debris, it's time for a flush regardless of mileage.

How to Refill & Bleed

The 3.6L Pentastar engine is somewhat notorious for trapping air in the cooling system, particularly in the heater core. Here is the best way to refill and bleed the system:

1. Drain the System: With the engine cold, open the petcock on the passenger side of the radiator to drain the old fluid.
2. Vacuum Fill (Highly Recommended): Using a pneumatic vacuum coolant filler is the professional way to refill the Gladiator. It pulls a vacuum on the entire cooling system and draws the new 50/50 mix in, entirely eliminating air pockets.
3. Manual Bleed Method: If you don't have a vacuum filler, locate the small bleeder screw on the thermostat housing (located on the front of the engine).
4. Open the bleeder screw slightly.
5. Slowly pour the 50/50 coolant mixture into the radiator until a steady stream of fluid (with no air bubbles) comes out of the bleeder valve. Close the bleeder valve snugly (do not overtighten, as the housing is plastic).
6. Fill the radiator to the top and top off the expansion tank.
7. Start the engine and turn the heater to the highest setting. Let the engine reach operating temperature until the thermostat opens and both radiator hoses are hot.
8. Shut the engine off, let it cool completely, and recheck the fluid level in the reservoir, topping off as needed.

Common Cooling System Issues

While the 2025 Gladiator is generally robust, the 3.6L Pentastar engine family does have a few known cooling system weak points to watch out for as the miles add up:

• Oil Filter Housing/Cooler Leaks: This is by far the most common issue on the 3.6L engine. The plastic housing that holds the oil filter and interfaces with the oil cooler sits in the "V" of the engine block. Over time, the plastic can warp or crack, leading to oil and coolant pooling in the engine valley and dripping down the back of the transmission.
• Thermostat Housing Leaks: The plastic thermostat housing can become brittle and weep coolant over time. It's good practice to replace the thermostat and housing as a single unit when doing a major coolant service.
• Radiator Seam Failure: Off-roading can put twisting stress on the chassis. Occasionally, this stress, combined with thermal cycling, can cause the crimped seams where the plastic radiator side tanks meet the aluminum core to develop slow leaks.

If you suspect a leak, notice your temperature gauge creeping up, or just need a professional coolant flush using the correct vacuum equipment, don't put it off. Find a trusted shop on Repairius.