2018 Ram 1500 Coolant Capacity & Type

A 2018 Ram 1500 holds between 10.1 and 14.1 quarts (9.6 to 13.3 liters) of coolant, depending on the engine.

Quick Answer

• Total Capacity: 10.1 qts (3.6L V6), 14.1 qts (5.7L V8)
• OEM Coolant Spec: Mopar 10-Year/150,000 Mile OAT Coolant (MS-12106)
• Coolant Color: Purple
• Chemistry: OAT (Organic Additive Technology)
• Mix Ratio: 50/50 with distilled water (pre-mixed is recommended)

Capacity by Engine Option

The specific cooling system capacity for your 2018 Ram 1500 varies by engine. Using the correct amount of coolant is critical to ensure proper engine temperature regulation.

Note: These values represent the total system capacity. A simple drain-and-refill may use less fluid, typically 60-70% of the total, as some old coolant will remain in the engine block and heater core.

Flush Interval

Ram specifies a very long initial service interval for the factory-fill OAT coolant, but this can change based on how you use your truck.

• Normal Service: The recommended flush interval under normal driving conditions is 10 years or 150,000 miles, whichever comes first.
• Severe Duty: If your truck is used for frequent towing, heavy hauling, extensive idling, or operating in extreme temperatures, it falls under a severe duty cycle. While the manufacturer doesn't specify an alternative, most technicians recommend shortening the interval to 75,000–100,000 miles to provide an extra margin of protection for these hard-working engines.

Using the correct Mopar MS-12106 OAT coolant is essential. Mixing it with other coolant types (like the older HOAT coolant, which was orange/pink) can cause the coolant to gel, leading to blockages, corrosion, and potential engine damage.

How to Refill & Bleed

Properly refilling and bleeding the cooling system is crucial to prevent air pockets, which can cause overheating and damage.

1. Safety First: Ensure the engine is completely cool before opening the radiator cap or any part of the cooling system. The system is under pressure when hot.
2. Drain: Place a large catch pan under the radiator and open the petcock (drain plug) at the bottom corner of the radiator.
3. Refill: Once drained, close the petcock. Slowly fill the system through the radiator cap opening (or coolant reservoir, if it's a pressurized degas bottle) with a 50/50 mix of MS-12106 OAT coolant and distilled water.
4. Bleed the System: Air must be purged from the system.
   • For 3.6L V6 & 5.7L V8 engines: These models typically have an air bleed screw located on the thermostat housing. Open this screw slightly while filling. When a steady stream of coolant comes out with no air bubbles, close the screw.
   • Vacuum-Fill Recommended: For a guaranteed air-free fill, professional shops (and savvy DIYers) use a vacuum-fill tool. This device pulls the entire cooling system into a deep vacuum and then uses that vacuum to draw coolant into every passage, eliminating the chance of air pockets.
5. Final Check: After filling, start the engine with the heater on high and let it warm up to operating temperature. This circulates coolant through the heater core. Monitor the coolant level in the reservoir and top it off as needed as the remaining air works its way out. Check for any leaks.

Common Cooling System Issues

This generation of Ram 1500 (2009-2018) is generally reliable, but some common cooling system issues have been noted:

• Water Pump Failure: Particularly on the 5.7L HEMI, the water pump bearing or seal can fail. Symptoms include a coolant leak from the front of the engine (from the pump's "weep hole") or a grinding noise.
• Radiator Leaks: The plastic end tanks crimped onto the aluminum core of the radiator can develop cracks or leaks over time, especially after 100,000 miles. Look for coolant stains on the radiator itself or drips underneath the front of the truck.
• Thermostat Issues: A thermostat can fail stuck-closed (causing rapid overheating) or stuck-open (preventing the engine from reaching full operating temperature, which reduces fuel efficiency and can trigger a check engine light).

Regularly inspecting your coolant level and checking hoses for softness or cracking can help you catch these issues before they lead to a breakdown.

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