This procedure drains and replaces the rear differential fluid in a 2014-2018 Chevrolet Silverado 1500 with 5.3L V8 engine, ensuring proper lubrication and extending differential life.

Warnings

Tools required

Parts

• Rear differential cover gasket × 1 — GM 88958341 or equivalent
• RTV silicone sealant (if gasket not available) × 1 — Permatex Ultra Grey 82194 or equivalent

Fluids

• ACDelco 75W-90 Synthetic Gear Oil — 2 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow differential to cool if vehicle was recently driven
3. Raise rear of vehicle using jack and support with jack stands rated for vehicle weight
4. Ensure vehicle is stable before working underneath
5. Position drain pan under rear differential

Procedure

1. 1

   Locate and clean differential cover
   Locate the rear differential cover on the rear axle assembly. Clean the exterior of the differential cover and surrounding area with brake cleaner to prevent dirt from entering during service. Identify all differential cover bolts (typically 10 bolts around the perimeter).
2. 2

   Loosen differential cover bolts
   Using a 13mm socket, loosen all differential cover bolts approximately 2-3 turns each, but do not remove. Start with the top bolts and work your way around. This allows the cover to break seal and fluid to begin draining in a controlled manner.
   ⚠Fluid will begin draining once seal is broken. Ensure drain pan is properly positioned.
3. 3

   Break seal and drain fluid
   Carefully loosen the bottom bolts further to allow the cover to tilt and drain fluid. You may need to gently pry the cover at the bottom edge with a scraper to break the seal. Allow fluid to drain completely into the drain pan. This may take 5-10 minutes.
   ⚠Support the cover as you remove final bolts to prevent it from falling.
4. 4

   Remove differential cover
   Once fluid has drained, remove the remaining bolts and carefully remove the differential cover. Some residual fluid will drain when cover is removed. Set cover aside on shop rags.
5. 5

   Inspect and clean differential housing
   Inspect the inside of the differential for metal shavings or debris. A small amount of fine metallic residue on the magnetic drain plug is normal. Excessive chunks or material may indicate wear. Wipe the inside of the differential housing opening with clean shop rags, being careful not to push debris into the gears.
6. 6

   Clean cover and mating surfaces
   Use a gasket scraper to remove all old gasket material and RTV from both the differential cover and the housing mating surface. Clean thoroughly with brake cleaner and wipe dry. Both surfaces must be completely clean and free of oil residue for proper seal.
   ℹ️Do not use abrasive pads that could gouge the sealing surfaces.
7. 7

   Install new gasket
   Place new differential cover gasket onto the cover, aligning all bolt holes. If using RTV sealant instead of a gasket, apply a continuous 3-4mm bead around the inside of the bolt holes on the cover. If your vehicle has a magnetic drain plug on the cover, ensure it is clean.
8. 8

   Reinstall differential cover
   Carefully position the differential cover with gasket back onto the housing, ensuring proper alignment. Start all bolts by hand to ensure they thread correctly. Tighten bolts in a cross-pattern (star pattern) to ensure even seating of the gasket. If using RTV, allow 10-15 minutes for initial setup before filling.
   ℹ️Tighten in multiple passes, gradually increasing torque to final specification to prevent gasket damage.
   Torque spec

   Differential Cover Bolts35 Nm (26 lb-ft)
9. 9

   Locate and access fill plug
   Locate the differential fill plug on the front of the differential housing. It is typically a square head plug or 3/8" drive socket fitting. Clean area around fill plug and remove it using appropriate tool. Set plug aside with a clean rag.
10. 10

    Fill differential with gear oil
    Using a fluid pump or funnel with extended hose, add ACDelco 75W-90 Synthetic Gear Oil through the fill hole. Fill until fluid begins to seep out of the fill hole opening (approximately 2 quarts). If equipped with G80 locking differential, add 4 oz of limited-slip additive to the fluid. The differential is properly filled when fluid reaches the bottom of the fill hole.
    ℹ️Check your RPO codes or owner's manual to confirm if vehicle has G80 locking differential which requires limited-slip additive.
11. 11

    Reinstall fill plug
    Clean the fill plug threads and reinstall into the differential housing. Hand-tighten, then snug with a ratchet. The fill plug does not require high torque, just snug to prevent leaks (typically 24 Nm / 18 lb-ft, though not in torque spec list - use hand-tight plus 1/4 turn).
12. 12

    Check for leaks
    Wipe down the differential cover and fill plug area. Inspect all areas for signs of leakage. If using RTV sealant, allow recommended cure time per product instructions before driving.

Reassembly

1. Lower vehicle from jack stands
2. Dispose of used differential fluid at appropriate recycling facility
3. Clean tools and work area

Verification

• Start engine and allow to idle for 1-2 minutes
• Drive vehicle forward and reverse several times to circulate new fluid
• Re-inspect differential cover and fill plug for leaks after test drive
• Check fluid level after 50-100 miles of driving and top off if necessary
• Monitor for leaks over the next few days of normal driving

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