Drain and refill the rear differential with fresh GL-5 gear oil to maintain proper lubrication of the ring and pinion gears.

Warnings

Tools required

Parts

• Differential cover gasket × 1 — Use OEM specification or RTV silicone gasket maker

Fluids

• 75W-90 GL-5 Gear Oil — 2 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Place wheel chocks in front of front wheels
3. Raise rear of vehicle using jack and secure on jack stands at the rear frame rails or axle housing spring perches
4. Verify vehicle is stable and level before working underneath
5. Position drain pan under differential cover

Procedure

1. 1

   Inspect differential identification tag
   Locate the identification tag bolted to one of the differential cover bolts. Note any information about limited-slip additive requirements or gear ratio. This tag should be reinstalled on reassembly.
2. 2

   Remove differential cover bolts
   Using a 1/2" socket, remove all 10 bolts securing the differential cover. Start by loosening the top bolts first, then progressively loosen lower bolts. Leave two upper bolts partially threaded (2-3 turns) to control cover removal.
3. 3

   Drain differential fluid
   Carefully pry the bottom of the differential cover away from the housing using a gasket scraper or flat blade screwdriver. Allow fluid to drain into the pan. Once flow slows, remove the remaining two bolts and fully remove the cover. Tilt cover to drain remaining fluid into pan.
4. 4

   Clean differential cover and housing mating surface
   Remove all old gasket material from both the differential housing flange and the inside of the cover using a gasket scraper. Use a wire brush if necessary. Clean surfaces thoroughly with shop rags. Inspect the drained fluid for metal shavings or debris; small amounts of fine particles are normal, but large chunks indicate gear wear.
5. 5

   Inspect ring and pinion gears
   With the cover removed, visually inspect the ring gear teeth for chips, scoring, or unusual wear patterns. Check for any loose bolts or components. This is an opportunity to identify potential issues before refilling.
6. 6

   Install new gasket on differential cover
   Place a new paper gasket on the differential cover, aligning all bolt holes. Alternatively, apply a 1/8" bead of RTV silicone gasket maker around the cover perimeter, circling each bolt hole. If using RTV, allow 10 minutes tack time before installation.
7. 7

   Reinstall differential cover
   Position the cover with gasket onto the differential housing, ensuring the identification tag is under one of the bolt heads. Start all 10 bolts by hand. Tighten bolts in a criss-cross pattern progressively to 15-20 ft-lb final torque. Do not overtighten, as this can distort the cover and cause leaks.
   ⚠Overtightening differential cover bolts can warp the thin stamped steel cover and cause leaks. Use moderate torque only.
8. 8

   Refill differential with gear oil
   Locate the fill plug on the passenger side of the differential housing (if equipped with separate fill plug) or fill through the cover bolt hole. Using a fluid pump or squeeze bottle, add 2.0 quarts of 75W-90 GL-5 gear oil. If the differential is Positraction-equipped and requires friction modifier, add the appropriate amount per the tag specification. Fluid level should reach the bottom of the fill plug hole or be approximately 1/2" below the ring gear.
9. 9

   Check for leaks
   Wipe the differential cover clean with a shop rag. Allow the differential to sit for several minutes after filling, then inspect the cover/gasket area for any signs of leakage. A more thorough check should be performed after the test drive. Shut off engine and inspect the cover gasket area for any signs of leakage. If leaks are present, tighten bolts slightly or verify gasket installation.

Reassembly

1. Lower vehicle from jack stands
2. Remove wheel chocks
3. Dispose of used gear oil at an appropriate recycling facility

Verification

• Test drive vehicle for 5-10 miles, making several turns in both directions to distribute fluid through limited-slip clutches if equipped
• Re-inspect differential cover for leaks after test drive
• Listen for any abnormal whining or grinding noises from the rear end during acceleration and deceleration
• Check fluid level again after test drive to confirm proper fill

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