This procedure drains and refills the rear differential with fresh Mopar 75W-140 synthetic gear lubricant to maintain proper lubrication and extend differential lifespan.

Warnings

Tools required

Parts

• Differential cover gasket (if using gasket instead of RTV) × 1 — Use OEM specification or RTV sealant

Fluids

• Mopar 75W-140 Synthetic Gear Lubricant — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Chock front wheels securely
3. Raise rear of vehicle and support on jack stands at frame rails
4. Ensure differential has cooled to safe handling temperature
5. Clean exterior of differential cover and surrounding area to prevent contamination

Procedure

1. 1

   Remove differential cover bolts
   Using a 10mm socket, loosen all differential cover bolts in a criss-cross pattern. Leave the top two bolts partially threaded to prevent the cover from falling when fluid drains.
2. 2

   Drain differential fluid
   Position drain pan beneath differential cover. Carefully remove the remaining cover bolts and allow the cover to tilt down, draining fluid into the pan. Once fluid flow stops, remove the cover completely and set aside.
   ⚠Fluid will rush out quickly when cover is loosened. Keep hands clear of the fluid stream.
3. 3

   Inspect internal components
   With cover removed, visually inspect the ring and pinion gears for abnormal wear, chips, or damage. Check for excessive metal shavings in the drained fluid (light metallic residue is normal). Inspect the magnetic drain plug for excessive metallic buildup.
   ℹ️Excessive metal particles or gear damage indicates potential differential problems requiring further diagnosis.
4. 4

   Clean mating surfaces
   Use a gasket scraper to carefully remove all old RTV sealant or gasket material from both the differential housing and cover mating surfaces. Clean surfaces thoroughly with brake cleaner and lint-free rags. Ensure no debris falls into the differential housing.
5. 5

   Apply RTV sealant to cover
   Apply a continuous 3-4mm bead of RTV silicone sealant to the differential cover mating surface. Run the bead around the inner side of the bolt holes. Sealant must be continuous with no gaps.
   ℹ️Do not use excessive sealant as it may squeeze into the differential and contaminate the fluid. If using a pre-cut gasket instead of RTV, no sealant is required.
6. 6

   Install differential cover
   Position the differential cover onto the housing, aligning all bolt holes. Install all cover bolts hand-tight. Using a torque wrench and criss-cross pattern, tighten bolts to specification in multiple passes (50%, 75%, then 100% torque).
   ⚠If using RTV sealant, cover must be installed within 10 minutes of sealant application before it begins to cure.
   Torque spec

   Differential Cover Bolts39 Nm (29 lb-ft)
7. 7

   Fill differential with gear oil
   Locate the fill plug on the differential cover (upper plug if two plugs present). Remove fill plug. Using a fluid transfer pump or squeeze bottle, add Mopar 75W-140 synthetic gear lubricant until fluid level reaches the bottom of the fill hole and begins to seep out. Install and hand-tighten the fill plug.
   ℹ️Differential requires approximately 2 quarts. Fill until fluid reaches fill hole; do not overfill.
8. 8

   Allow sealant to cure
   If RTV sealant was used, allow at least 1 hour cure time before lowering vehicle or driving. Refer to sealant manufacturer's instructions for full cure time (typically 24 hours for maximum strength).

Reassembly

1. Verify fill plug is securely installed
2. Wipe any spilled gear oil from differential housing exterior
3. Lower vehicle from jack stands
4. Remove wheel chocks

Verification

• Inspect differential cover for any signs of fluid leakage around the seal
• Test drive vehicle and listen for any unusual noises from rear differential
• After first 50 miles, re-inspect cover area for leaks
• Check fluid level at fill plug after 500 miles to ensure proper level is maintained

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