2021 Ram 3500 Fluid Type Specifications

Quick reference

Fluid	Type/Spec	Capacity
Engine Oil (Gas)	SAE 5W-30, Mopar MS-6395, API SN/SP	7.0 quarts (6.6 liters)
Engine Oil (Diesel)	SAE 5W-40, Mopar MS-10902, API CJ-4/CK-4	12.0 quarts (11.3 liters)
Engine Coolant	Mopar OAT Antifreeze/Coolant, MS-90032 (Purple)	~19.0 quarts (18.0 liters)
Transmission (68RFE)	Mopar ATF+4, MS-9602	17.5 quarts (16.5 liters) total fill
Transmission (Aisin AS69RC)	Aisin Warner ATF M31 (AW-1 equivalent), MS-9756	13.7 quarts (13.0 liters) total fill
Transfer Case (BW 44-46/44-48)	Mopar ATF+4, MS-9602	1.8-2.0 quarts (1.7-1.9 liters)
Front Differential (11.5 AAM)	SAE 75W-90, API GL-5 (Non-LSD)	2.8 quarts (2.6 liters)
Front Differential (10.5 AAM)	SAE 75W-90, API GL-5 (Non-LSD)	2.3 quarts (2.2 liters)
Rear Differential (12 AAM)	SAE 75W-140, API GL-5, with LSD additive (if equipped)	4.2 quarts (4.0 liters)
Rear Differential (11.8 AAM)	SAE 75W-90, API GL-5, with LSD additive (if equipped)	4.0 quarts (3.8 liters)
Brake Fluid	Mopar DOT 3, MS-4003	As needed
Power Steering	Mopar ATF+4, MS-9602	As needed
Washer Fluid	Mopar Windshield Washer Concentrate	As needed
Diesel Exhaust Fluid (DEF)	API Certified ISO 22241	5.0 gallons (18.9 liters)

Engine Oil

For the 2021 Ram 3500, engine oil specifications vary significantly depending on whether you have the gasoline or Cummins turbodiesel engine.

Gasoline Engines (6.4L HEMI V8):

The 6.4L HEMI V8 engine requires SAE 5W-30 engine oil that meets Chrysler material standard Mopar MS-6395. It should also be API SN or SP certified. The capacity for an oil change with a new filter is approximately 7.0 quarts (6.6 liters). Using oil that does not meet the MS-6395 standard can lead to premature wear and potential engine damage. Regular oil changes, typically every 7,500 to 10,000 miles or 6 to 12 months (whichever comes first), are crucial for the longevity of your engine. Always verify the exact interval in your owner's manual, especially if your truck is used for heavy-duty applications like towing or prolonged idling, as these conditions may warrant more frequent changes.

Diesel Engines (6.7L Cummins Turbo Diesel):

For the robust 6.7L Cummins Turbo Diesel, the recommended engine oil is SAE 5W-40 that meets Chrysler material standard Mopar MS-10902. It must also be API CJ-4 or, for newer engines, CK-4 certified. The capacity for this engine is significantly higher at approximately 12.0 quarts (11.3 liters) with a new filter. Adhering to the correct API spec is vital for the diesel particulate filter (DPF) and other emissions equipment. Using non-compliant oil can severely shorten the lifespan of these components. Cummins engines are known for their durability, but proper maintenance with the correct fluids is paramount. Oil change intervals typically range from 10,000 to 15,000 miles or 6 to 12 months, but always refer to your owner's manual for the precise schedule based on your usage and duty cycle.

Engine Coolant

The 2021 Ram 3500, regardless of engine type, uses Mopar OAT (Organic Additive Technology) Antifreeze/Coolant, specified by Chrysler material standard MS-90032. This coolant is typically purple in color. The total system capacity is approximately 19.0 quarts (18.0 liters). It is crucial to use only OAT coolant that meets the MS-90032 specification. Mixing OAT coolant with other types, such as HOAT (Hybrid Organic Additive Technology) or traditional green coolants, can lead to chemical reactions that form gelling or precipitates, causing blockages in the cooling system, overheating, and severe engine damage. Always perform a complete flush if switching coolant types or if contamination is suspected. Coolant should be checked regularly for proper level and condition, and typically replaced every 5 years or 100,000 miles, though heavy-duty use might require more frequent changes. Consult your owner's manual.

Transmission Fluid

The 2021 Ram 3500 can be equipped with different automatic transmissions, each with specific fluid requirements.

68RFE Automatic Transmission:

If your Ram 3500 has the 68RFE automatic transmission, it requires Mopar ATF+4, specified by Chrysler material standard MS-9602. The total fill capacity is about 17.5 quarts (16.5 liters). Never use "universal" ATF or fluids like Dexron/Mercon, as they are not compatible with the 68RFE and can cause transmission damage. ATF+4 is a highly engineered fluid designed specifically for Chrysler and Ram transmissions. Fluid and filter changes are typically recommended every 60,000 to 120,000 miles, depending on usage. Heavy towing or frequent stop-and-go driving may necessitate more frequent changes. Check your owner's manual for your specific maintenance schedule.

Aisin AS69RC Automatic Transmission:

Rams equipped with the Aisin AS69RC heavy-duty automatic transmission require a different fluid: Aisin Warner ATF M31, which is an AW-1 equivalent. This fluid meets Chrysler material standard MS-9756. The total fill capacity is approximately 13.7 quarts (13.0 liters). Just like with the 68RFE, using improper fluid can lead to catastrophic transmission failure. Always verify the fluid type against your owner's manual or an OEM service reference based on your transmission model. Service intervals for the Aisin transmission are generally similar to the 68RFE, with considerations for severe duty cycles.

Transfer Case Fluid

The 2021 Ram 3500 with 4WD/AWD typically uses a BorgWarner transfer case (often BW 44-46 or BW 44-48). These transfer cases require Mopar ATF+4, meeting Chrysler material standard MS-9602. The capacity is usually between 1.8 and 2.0 quarts (1.7-1.9 liters). The use of ATF+4 in the transfer case is common across many Ram models. Check your owner's manual for the specific transfer case model and its fluid capacity. Transfer case fluid should typically be inspected and possibly changed every 60,000 to 80,000 miles, especially if you frequently engage 4WD or perform heavy towing.

Differential Fluid

Ram 3500 trucks often come with AAM (American Axle & Manufacturing) differentials, with different sizes and capacities depending on the trim and options. It's crucial to identify your specific axle before servicing.

Front Differential:

For the front differential (commonly 11.5 AAM or 10.5 AAM), the specification is typically SAE 75W-90 API GL-5 gear oil. The 11.5 AAM holds about 2.8 quarts (2.6 liters), while the 10.5 AAM holds approximately 2.3 quarts (2.2 liters). Most front differentials are open and do not require friction modifiers. Verify your specific axle and capacity in your owner's manual.

Rear Differential:

Rear differentials on the Ram 3500 are often 12 AAM or 11.8 AAM. For the 12 AAM, the required fluid is typically SAE 75W-140 API GL-5 gear oil. If your truck is equipped with a limited-slip differential (LSD), a friction modifier additive must be used. Many suitable 75W-140 GL-5 oils already contain the necessary friction modifier, but always verify. Capacity is around 4.2 quarts (4.0 liters). For the 11.8 AAM, some models may specify SAE 75W-90 API GL-5 with an LSD additive if equipped. Capacity is around 4.0 quarts (3.8 liters). Differential fluid service intervals can range from 30,000 to 60,000 miles, with more frequent changes recommended for heavy towing or off-road use. Always refer to your owner's manual.

Brake Fluid

The 2021 Ram 3500 uses Mopar DOT 3 Brake Fluid, which meets Chrysler material standard MS-4003. Brake fluid is hygroscopic, meaning it absorbs moisture over time, which lowers its boiling point and can lead to corrosion in the braking system. Therefore, it should be flushed and replaced periodically, typically every 2-3 years, regardless of mileage. Never mix DOT 3 with DOT 4, 5, or 5.1 fluids without specific instruction from the OEM, and never use DOT 5 (silicone-based) fluid in a system designed for DOT 3/4. The capacity is "as needed" for topping off or a full bleed/flush.

Power Steering Fluid

The power steering system in the 2021 Ram 3500 typically uses Mopar ATF+4, specified by Chrysler material standard MS-9602. This is the same fluid used in many Ram automatic transmissions. Ensure you use ATF+4 and not a generic power steering fluid. Using the incorrect fluid can lead to pump whine, steering issues, and premature component failure. Power steering fluid doesn't have a strict replacement interval but should be checked periodically for level and condition. A flush may be recommended if the fluid appears dark or contaminated.

Washer Fluid

For optimal visibility, use Mopar Windshield Washer Concentrate mixed with water according to package directions, or a high-quality pre-mixed windshield washer fluid. In cold climates, ensure the fluid has adequate freeze protection to prevent it from freezing in the reservoir and lines. The capacity is "as needed" to fill the reservoir.

Diesel Exhaust Fluid (DEF)

For 2021 Ram 3500 models equipped with the 6.7L Cummins Diesel, Diesel Exhaust Fluid (DEF) is essential for the Selective Catalytic Reduction (SCR) system. DEF must be API Certified and meet ISO 22241 standards. The DEF tank capacity is approximately 5.0 gallons (18.9 liters). Using non-compliant DEF or contaminated fluid can damage the SCR system and lead to costly repairs. Store DEF in a cool, dry place and be mindful of its shelf life, as it can degrade over time. The truck will provide warnings as the DEF level gets low, and if allowed to run out, the engine's power will be severely limited until the tank is refilled.

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