2018 Ram 1500 Fluid Specs & Capacities

Quick Reference: 2018 Ram 1500 Fluid Specs

Fluid	Type/Spec	Capacity
Engine Oil (3.6L V6)	SAE 5W-20 (API SP, Chrysler MS-6395)	6 quarts / 5.7 liters
Engine Oil (5.7L V8)	SAE 5W-20 (API SP, Chrysler MS-6395)	7 quarts / 6.6 liters
Engine Oil (3.0L EcoDiesel)	SAE 5W-40 (API CJ-4/CK-4, Chrysler MS-10902)	10.5 quarts / 9.9 liters
Engine Coolant	Mopar OAT (purple), 10yr/150k mi (MS-12106)	14.1 - 18.2 quarts / 13.3 - 17.2 liters
Transmission Fluid (8-spd)	Mopar ZF 8&9 Speed ATF (MS-90030-A2)	9.0 quarts / 8.5 liters (approx. fill)
Transfer Case Fluid	Mopar BW44/48 ATF	~1.5 quarts / 1.4 liters
Front Differential (4WD)	SAE 75W-85 Synthetic Gear Lubricant	~1.2 quarts / 1.1 liters
Rear Differential	SAE 75W-90 Synthetic Gear Lubricant	2.4 - 2.6 quarts / 2.3 - 2.5 liters
Brake Fluid	DOT 3 / DOT 4	As needed
Power Steering Fluid	Electric Power Steering (EPS) - No Fluid	N/A
Washer Fluid	-30°F / -34°C Bug & Tar Remover	~1 gallon / 3.8 liters
Diesel Exhaust Fluid (DEF)	API Certified (ISO 22241)	8 gallons / 30.3 liters

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Engine Oil

For the 2018 Ram 1500, selecting the correct engine oil is critical for the longevity and performance of its powertrain. The specific oil required depends on the engine.

• 3.6L Pentastar V6 & 5.7L HEMI V8: Both gasoline engines require an SAE 5W-20 viscosity grade oil. It must meet Chrysler MS-6395 and be API Certified (look for the "SP" donut). Using a full synthetic oil is highly recommended for optimal performance and protection, especially in extreme temperatures. The 3.6L V6 has a capacity of 6 quarts, while the 5.7L V8 takes 7 quarts.
• 3.0L EcoDiesel V6: The diesel engine has different requirements. It specifies a robust SAE 5W-40 synthetic diesel oil meeting Chrysler MS-10902 and API CJ-4 or CK-4 standards. These oils are formulated to handle the higher combustion pressures and soot levels inherent in diesel engines. The capacity is significantly larger at 10.5 quarts.

Pitfall: Never use conventional oil where synthetic is specified, and do not extend oil change intervals beyond the manufacturer's recommendation, which is determined by the oil life monitoring system.

Engine Coolant

The 2018 Ram 1500 left the factory with a specific Mopar OAT (Organic Acid Technology) coolant, which is purple in color. This is a long-life coolant, formulated for 10 years or 150,000 miles. The official specification is Mopar MS-12106. When topping off or refilling the system, it is crucial to use this exact type of coolant or a compatible OAT equivalent.

Pitfall: Never mix coolant types. Adding a different color coolant (like the older orange/red HOAT or green IAT) can cause the coolant to gel, leading to clogged heater cores, radiators, and catastrophic engine overheating. If you are unsure what is in the system, a complete flush and fill is the safest option.

Transmission Fluid

All 2018 Ram 1500 models are equipped with an 8-speed automatic transmission. This advanced transmission requires a very specific fluid: Mopar ZF 8&9 Speed ATF, which meets Chrysler spec MS-90030-A2. This is a low-viscosity, full synthetic fluid designed for smooth shifting and long-term durability.

Checking the fluid level is not a simple dipstick operation; it requires a scan tool to monitor transmission temperature and a specific fill procedure. A full fluid and filter service is a complex job best left to a professional.

Pitfall: Absolutely do not use "Universal" or multi-vehicle ATF. Using the wrong fluid (like ATF+4, Dexron VI, or Mercon LV) will cause severe shifting problems, torque converter shudder, and ultimately, transmission failure.

Transfer Case & Differential Fluids

For 4WD models, the transfer case and differentials have their own lubrication needs.

• Transfer Case: The BorgWarner transfer cases in the Ram 1500 require a specific fluid, Mopar BW44/48 ATF. Do not substitute standard ATF.
• Front Differential (4WD): The front axle calls for an SAE 75W-85 Synthetic Gear Lubricant.
• Rear Differential: Most 2018 Ram 1500s use an SAE 75W-90 Synthetic Gear Lubricant. If your truck is equipped with a limited-slip differential (LSD), ensure the gear oil either contains the necessary friction modifier or that a separate bottle of Mopar Limited-Slip Additive is added with the gear oil to prevent chatter and binding.

Brake & Power Steering Fluid

• Brake Fluid: The hydraulic brake system requires DOT 3 brake fluid. DOT 4 is an acceptable substitute as it has a higher boiling point, but the two should not be mixed if possible. The system should be flushed and the fluid replaced every 2-3 years, as brake fluid is hygroscopic (absorbs moisture), which can lead to corrosion and reduced braking performance.
• Power Steering: The 2018 Ram 1500 is equipped with Electric Power Steering (EPS). This system uses an electric motor to assist with steering and does not use any hydraulic fluid. There is no reservoir to check or fill.

Washer Fluid & DEF (Diesel Models)

• Washer Fluid: Use any quality, commercial-grade windshield washer fluid. A "-30°F" or lower freeze protection rating is recommended for winter climates.
• Diesel Exhaust Fluid (DEF): For the 3.0L EcoDiesel, API Certified DEF (ISO 22241) is required. This fluid is injected into the exhaust stream to reduce NOx emissions. The DEF tank is located near the fuel tank and has a blue cap. Keep the tank topped off to avoid vehicle speed limitations, and only purchase DEF from reputable sources to prevent contamination of the sensitive SCR (Selective Catalytic Reduction) system.

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