2021 Jeep Wrangler — Coolant Capacity, Type, and Maintenance Guide

The 2021 Jeep Wrangler holds between 9.9 and 14.4 quarts (9.4 to 13.6 liters) of coolant, depending on which engine option is under the hood.

Whether you are hitting the trails or commuting in your JL Wrangler, keeping the cooling system in peak condition is vital for preventing engine overheating and premature wear. Jeep has used a few different engines for the 2021 model year, including the 2.0L turbocharged inline-four, the classic 3.6L Pentastar V6, the 3.0L EcoDiesel, the 6.4L Hemi V8 (Rubicon 392), and the 4xe Plug-in Hybrid. Each has its own specific cooling system demands, but they all share the exact same strict coolant formulation requirements.

Here is everything you need to know about servicing the cooling system on your 2021 Jeep Wrangler.

Quick Answer

• Total Cooling System Capacity: 9.9 to 14.4 quarts (9.4 to 13.6 liters) depending on the engine.
• OEM Coolant Spec: Mopar 10-Year/150,000-Mile Formula OAT (Organic Additive Technology). Manufacturer spec number MS-12106.
• Coolant Color: Purple (often appears pinkish-purple). Never mix this with older orange HOAT coolant!
• Mix Ratio: 50/50 mix of Mopar OAT concentrate and distilled water, or simply use a 50/50 pre-mixed solution.

Capacity by Engine Option

Because the JL Wrangler offers such a wide variety of powertrains, you will need to check your specific engine to know exactly how much coolant to buy for a complete flush.

Note: Capacities are approximate. Always buy an extra gallon of 50/50 mix to ensure you have enough for topping off after bleeding the system.

Flush Interval

Chrysler/Jeep engineered the MS-12106 OAT coolant to be exceptionally long-lasting, but it still degrades over time.

• Normal Duty: Replace every 10 years or 150,000 miles (whichever comes first).
• Severe Duty: Replace every 100,000 miles. Severe duty applies if you frequently tow, idle extensively, drive off-road in dusty/muddy conditions, or operate primarily in extreme temperatures.

As a master technician, I highly recommend checking the freeze point and pH of the coolant around the 5-year/75,000-mile mark, as degraded coolant can cause expensive damage to internal components.

How to Refill & Bleed

Modern Jeeps can be notoriously difficult to bleed because air pockets easily become trapped in the heater core and upper coolant hoses.

1. Drain the System: Open the radiator drain petcock (located on the lower passenger side of the radiator) and let the old fluid drain into a catch pan.
2. Vacuum Fill (Recommended): The absolute best way to refill a 2021 Wrangler is by using a vacuum coolant refill tool. This pulls a vacuum on the empty system and draws the new Mopar OAT fluid in, completely eliminating air pockets.
3. Manual Bleed (If vacuum tool is unavailable):
   • Slowly fill the radiator and the coolant reservoir to the MAX line.
   • Locate the bleeder screw (on the 3.6L, it is typically on the thermostat housing). Open it slightly until a steady stream of fluid comes out, then close it.
   • Start the engine with the radiator cap off and turn the cabin heater to the maximum heat setting.
   • Let the engine idle until it reaches operating temperature and the thermostat opens (you will feel the upper radiator hose get hot).
   • Top off the fluid as the level drops. Squeeze the upper radiator hose to help burp out trapped air.
   • Once the level stabilizes and you have hot air blowing from the vents, replace the cap. Monitor the reservoir level over the next few days of driving.

Common Cooling System Issues

The JL generation Wrangler (2018+) is incredibly capable, but it is not immune to cooling system faults. Keep an eye out for these common issues:

• Radiator Seam Leaks: The most frequent cooling issue on these Wranglers is a leak where the aluminum radiator core is crimped to the plastic side tanks. If you smell sweet coolant at the front of the grille, inspect the driver and passenger side radiator seams for a crusty purple residue.
• Oil Filter Housing Leaks (3.6L V6): The Pentastar V6 uses a plastic oil filter housing/oil cooler assembly nestled in the engine valley. As the plastic heat-cycles, it can warp and leak coolant or oil down the back of the engine block.
• Water Pump Weeping: While less common at low mileage, water pump shaft seals will eventually fail. Look for purple drips on the front of the engine block directly below the water pump pulley.

Maintaining your cooling system is the best way to keep your 2021 Wrangler ready for your next adventure. If you suspect a leak or need a professional coolant flush, do not wait for the temperature gauge to spike. Find a trusted shop on Repairius.