maintenance

Differential Service

for 1994–2007 Dodge Ram 2500 5.9L I6 Cummins Diesel · 4WD

Difficulty

Easy

Time

1.2 h

Tools

Steps

✓Fact-checked. Built from OLP's spec database, then independently fact-checked line by line with every correction applied. Master-tech sign-off by Chris Hackleman is queued. Cross-check torque values against the factory manual, and stop if anything looks unsafe. How our data is made.

This procedure covers draining, inspecting, and refilling both front and rear differentials on a 4WD Dodge Ram 2500 with the 5.9L Cummins diesel engine.

Warnings

⚠Differential fluid may be hot if vehicle was recently driven. Allow adequate cooling time before service.

⚠Gear oil has a strong odor and can cause skin irritation. Use nitrile gloves and work in a well-ventilated area.

ℹ️Some models use removable drain plugs while others require cover removal for draining. Verify configuration before starting.

ℹ️If fluid shows metal contamination or unusual wear particles, further differential inspection may be required.

Tools required

3/8" drive ratchet and socket setEssential

Torque wrench (10-150 Nm range)Essential

Drain pan (minimum 8 quart capacity)Essential

Floor jack and jack standsEssential

Wheel chocksEssential

RTV silicone gasket maker (if equipped with cover bolts)

Gasket scraper or plastic scraper

Brake cleaner

Shop ragsEssential

Fluid transfer pump

Wire brush

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Parts

Front differential cover gasket or RTV sealant × 1 — Use OEM specification or high-temp RTV
Rear differential cover gasket or RTV sealant × 1 — Use OEM specification or high-temp RTV
Drain plug washer (if equipped with drain plug) × 2 — Copper or aluminum crush washer
Shop towels × 1 — Generic

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Fluids

75W-90 synthetic gear oil (front differential) — 3.5 qt
75W-90 synthetic gear oil (rear differential) — 5.5 qt

Preparation

Park vehicle on level surface and engage parking brake
Place wheel chocks behind front wheels
Raise rear of vehicle and support securely on jack stands at frame rail points
If servicing front differential, raise front of vehicle and support securely on jack stands
Allow differential to cool to safe working temperature if recently driven
Have drain pan and fresh gear oil ready before opening drain points

Procedure

1
Drain rear differential fluid
Position drain pan beneath rear differential. If equipped with drain plug, remove drain plug using appropriate socket and allow fluid to drain completely. If not equipped with drain plug, proceed to remove cover bolts in a crisscross pattern starting from top, leaving bottom bolts slightly tight. Carefully break cover seal and allow fluid to drain before fully removing cover. Inspect drained fluid for metal particles or contamination.
Torque spec
Drain Plug41 Nm (30 lb-ft)
2
Clean rear differential cover and housing
Once fluid is fully drained, remove rear differential cover completely if not already removed. Use gasket scraper to remove old gasket material or RTV from both cover and differential housing mating surfaces. Clean surfaces thoroughly with brake cleaner and shop rags. Inspect cover for cracks or damage. Check magnetic drain plug (if equipped) for excessive metal particles.
3
Inspect rear differential internals
With cover removed, visually inspect ring and pinion gears for excessive wear, pitting, or damage. Check gear tooth contact pattern if visible. Verify differential bearing condition and look for any signs of overheating or abnormal wear. If equipped with limited slip differential, note condition of clutch packs.
4
Reinstall rear differential cover
If using RTV sealant, apply continuous 1/8" bead around cover flange, circling all bolt holes on the outside. If using gasket, position new gasket on housing. Install cover and start all bolts by hand. Tighten cover bolts in a crisscross pattern to the axle-specific torque (typically ~30-35 ft-lbs for Dana/AAM covers; verify against the service manual for your axle model). If using RTV, allow 15-20 minutes cure time before filling. Install drain plug with new washer if applicable.
Torque spec
Drain Plug41 Nm (30 lb-ft)
5
Refill rear differential
Locate fill plug on rear differential housing (typically on front face or side). Remove fill plug. Using fluid pump or squeeze bottle, add 75W-90 synthetic gear oil (add Mopar limited-slip friction modifier if equipped with TracLok/limited-slip axle) through fill hole until fluid begins to seep from fill hole opening. Fluid should be level with bottom of fill hole. Rear differential capacity varies by axle model (Dana 70 or AAM 11.5") and is approximately 3.5 to 4 quarts; always fill to level of fill hole, not to a capacity measurement. Install and torque fill plug to specification.
ℹ️Rear differential capacity is approximately 5.5 quarts but fill to level of fill hole, not to capacity measurement.
Torque spec
Fill Plug41 Nm (30 lb-ft)
6
Drain front differential fluid
Reposition drain pan beneath front differential. If equipped with drain plug, remove drain plug and allow fluid to drain completely. If cover removal is required, remove cover bolts in crisscross pattern starting from top, leaving bottom bolts slightly tight. Break cover seal carefully and allow complete drainage. Inspect drained fluid for contamination.
Torque spec
Drain Plug41 Nm (30 lb-ft)
7
Clean front differential cover and housing
Remove front differential cover completely. Clean old gasket material or RTV from cover and housing mating surfaces using gasket scraper. Clean thoroughly with brake cleaner. Inspect internal components for wear or damage. Check magnetic drain plug for metal particles.
8
Reinstall front differential cover
Apply RTV sealant or position new gasket on front differential housing. Install cover and start all bolts by hand. Tighten cover bolts or cover screws in crisscross pattern to specified torque. If using RTV, allow adequate cure time. Install drain plug with new washer if equipped.
Torque spec
Drain Plug41 Nm (30 lb-ft)
9
Refill front differential
Remove fill plug from front differential housing. Add 75W-90 synthetic gear oil through fill hole until fluid reaches bottom of fill hole and begins to seep out. Front differential capacity is approximately 1.5 to 2 quarts depending on axle (Dana 44 or Dana 60); fill to level of fill hole opening rather than a capacity measurement. Install fill plug and torque to specification.
ℹ️Front differential capacity is approximately 3.5 quarts but fill to level of fill hole opening.
Torque spec
Fill Plug41 Nm (30 lb-ft)
10
Lower vehicle and verify
Wipe down both differentials to remove any spilled fluid. Double-check that all drain plugs and fill plugs are properly installed and torqued. Lower vehicle from jack stands to ground. Check underneath for any fluid leaks from covers or plugs.

Reassembly

Ensure all differential cover bolts are torqued in proper sequence
Verify drain plugs and fill plugs are tight and not leaking
Clean any spilled gear oil from differential housings and surrounding components
Dispose of used gear oil properly at recycling center

Verification

Start engine and let idle, then engage 4WD transfer case briefly to circulate front differential fluid
Drive vehicle 5-10 miles and recheck both differentials for leaks at covers and plugs
After 50-100 miles of driving, recheck fluid levels at fill plugs to ensure proper fill
Monitor for unusual noises from differentials during normal driving