2020 Ram 3500 Coolant Capacity and Type

Quick Answer

• Total Cooling System Capacity: 16.5 to 29.2 quarts (15.6 to 27.6 liters), depending on engine option.
• OEM Coolant Specification: Mopar 10-Year/150,000-Mile OAT (Organic Additive Technology), conforming to MS-12106. This coolant is typically purple.
• Mix Ratio: Use a 50/50 mixture of coolant concentrate and distilled water. Pre-mixed 50/50 versions are recommended for convenience and accuracy.

Capacity by Engine Option

The 2020 Ram 3500 offers two distinct engine choices, each with a different cooling system capacity. It is critical to know which engine your truck is equipped with before purchasing coolant.

Flush Interval

Adhering to the correct service interval is key to preventing corrosion and ensuring optimal engine temperature regulation.

• Normal Service: For the Mopar OAT MS-12106 coolant, the recommended service interval is up to 10 years or 150,000 miles, whichever comes first.
• Severe Duty: If the vehicle is operated under severe conditions—such as frequent towing, heavy hauling, extensive idling, or operating in extreme temperatures—it is wise to inspect the coolant quality more frequently and consider a flush sooner, potentially around the 100,000-mile mark.

How to Refill & Bleed

Properly refilling and bleeding the air from the cooling system is crucial, especially on modern trucks. Air pockets can cause overheating and damage to engine components.

1. Safety First: Ensure the engine is completely cool before opening the cooling system.
2. Access the System: On the 6.7L Cummins, the primary fill point is the expansion tank. The 6.4L HEMI has a radiator cap and a coolant reservoir.
3. Refill Slowly: Add the 50/50 coolant mixture to the appropriate reservoir/tank. Fill it slowly to allow air to escape as the fluid level rises.
4. Bleeding Procedure: While there isn't a specific manual bleed screw on all models, the recommended method for these trucks is to use a vacuum-fill tool. This tool pulls the system into a deep vacuum, removing all air pockets before coolant is drawn in. This is the most effective way to ensure a complete, air-free fill.
5. Alternative Method (Without Vacuum-Fill): If not using a vacuum-filler, fill the system, leave the cap off the expansion tank, and start the engine. Turn the cabin heater to its highest temperature and fan setting. Allow the engine to run until it reaches operating temperature, which allows the thermostat to open. You should see the coolant level drop as air is purged. Top off as needed. Repeat this process a few times after engine cool-downs to ensure all air is out.

Common Cooling System Issues

The 2019+ Ram Heavy Duty trucks are generally robust, but some common issues can arise:

• Water Pump Failure: Particularly on the 6.7L Cummins, water pump failure is a known potential issue. Symptoms include a coolant leak from the front of the engine, a whining noise, or rising engine temperatures.
• EGR Cooler Issues (Diesel): The exhaust gas recirculation (EGR) cooler can develop leaks, either internally (leading to white smoke from the exhaust) or externally. This can cause gradual coolant loss.
• Radiator and Hose Leaks: Like any vehicle, rubber hoses can degrade over time, and radiators can be damaged by road debris. Regular inspection of all hoses and connections is recommended.

Find a trusted shop on Repairius.