2021 Ram 2500 Fluid Type Specs
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As an ASE-Certified Master Technician, I'm here to provide a comprehensive guide to all factory-spec fluids for your 2021 Ram 2500. Using the correct fluids is paramount for the longevity and performance of your truck, ensuring it operates as the manufacturer intended.
Quick Reference
| Fluid | Type/Spec | Capacity |
|---|---|---|
| Engine Oil (Gas) | SAE 5W-20, API SN Plus/SP, Mopar MS-6395 | 7.0 quarts (6.6 liters) |
| Engine Oil (Diesel) | SAE 5W-40, API CK-4, Mopar MS-10902 | 13.0 quarts (12.3 liters) with filter |
| Engine Coolant | OAT (Organic Additive Technology), Mopar MS-90032 (Purple) | Verify in owner's manual / OEM service info |
| Transmission Fluid (8HP75 - 6.4L Hemi) | ZF LifeguardFluid 8, Mopar ZF 8-Speed ATF | 5.5-7.0 liters (pan drop); 10.0-11.0 liters (overhaul) |
| Transmission Fluid (68RFE Diesel) | Mopar ATF+4, MS-9602 | 7.0 quarts (6.6 liters) for filter change; 17.5 quarts (16.6 liters) total |
| Transfer Case (BW 44-47/44-48) | Mopar ATF+4, MS-9602 | 1.7-2.0 quarts (1.6-1.9 liters) |
| Front Differential (10.0 AAM) | SAE 75W-90, API GL-5, Mopar MS-9763 | 2.5-2.8 quarts (2.4-2.6 liters) |
| Rear Differential (11.5 AAM) | SAE 75W-90, API GL-5, Mopar MS-9763 | 4.0-4.2 quarts (3.8-4.0 liters) |
| Rear Differential (12.0 AAM) | SAE 75W-90, API GL-5, Mopar MS-9763 | 4.0-4.2 quarts (3.8-4.0 liters) |
| Brake Fluid | DOT 3 or DOT 4 (refer to cap) | Fill to MAX line |
| Power Steering Fluid | Mopar MS-5931, Power Steering Fluid +4 | Fill to MAX line |
| Washer Fluid | Mopar Windshield Washer Fluid or equivalent all-season formula | 1 gallon (3.8 liters) |
| DEF (Diesel Exhaust Fluid) | ISO 22241 (API DEF certified) | 5.0 gallons (18.9 liters) |
Engine Oil
6.4L Hemi V8 (Gasoline): Your 2021 Ram 2500 with the 6.4L Hemi requires SAE 5W-20 engine oil meeting API SN Plus or API SP specifications, and specifically meeting Stellantis/Mopar material standard MS-6395. The oil capacity is approximately 7.0 quarts (6.6 liters) with a filter change. Ram recommends oil changes every 10,000 miles or 12 months, or sooner under severe conditions like towing heavy loads or extensive idling.
6.7L Cummins Turbo Diesel: For the 6.7L Cummins, use an SAE 5W-40 engine oil that meets API CK-4 specifications and Mopar material standard MS-10902. The capacity is substantial, at 13.0 quarts (12.3 liters) with a filter change. Diesel engines place high demands on oil, so adhering to the manufacturer
More specs for the 2021 Ram 2500
Oil Capacity & Filter
Capacity, weight, filter PN, drain plug torque, change interval.
Coolant Capacity & Type
Total system capacity, OEM coolant spec, flush interval, bleed tips.
Transmission Fluid & Service
Trans model, fluid spec, capacity, filter PN, service interval.
Torque Specifications
Lug nuts, drain plug, caliper, axle nut, plug, key fasteners.
Brake Pad & Rotor Specs
Pad PNs, rotor size, min thickness, caliper torque.
Tire Size & Pressure
OEM size, cold psi, bolt pattern, wheel size, TPMS.
Battery Size & Group
Group size, CCA, AGM/flooded, dimensions, reset note.
A/C Refrigerant & Oil
R-134a or R-1234yf, charge oz, PAG oil spec.
Bulb Sizes (Headlight, Tail, Fog)
Headlight, fog, tail, turn, reverse, interior.
Factory Maintenance Schedule
Service intervals by mileage, severe-duty notes, known issues.
Towing Capacity & Payload
Max tow, payload, GVWR/GCWR, hitch class by trim.
Fuse Box Diagram & Amperage
Fuse box locations, layout, amps, and what each fuse controls.
Serpentine Belt Routing & Length
Belt routing, length, rib count, OEM + aftermarket PNs.
Wheel Alignment Specifications
Camber, caster, toe ranges (front & rear), adjustability notes.
Paint Color Codes
All factory colors with paint codes, sticker location, touch-up tips.
Wiper Blade Sizes
Driver/passenger/rear blade size, attachment, OEM + cross-refs.
Spark Plug Type & Gap
Plug PN, gap, torque, interval by engine.
Transmission & Axle Gear Ratios
Trans gear ratios, axle ratios, RPO codes, tow vs MPG impact.
Key Fob Programming
DIY programming steps, FCC ID, fob PN, battery, transponder.
Same spec — other model years
Maintenance & repair guides
2021 Ram 2500 Maintenance Schedule →
Available maintenance guidance; confirm the manufacturer schedule.
Repair planning references →
Plan the scope of work; detailed procedures need configuration-matched evidence.
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Values can vary by engine, trim and build date; check your VIN-specific service information. Updated 2026-06-23.