For 1990-2009 cars

1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Clean any dirt or foreign material from around the rear axle housing drain plug.
3. Remove the rear axle housing drain plug.
4. Verify that the axle lubricant level is within the following range:

• | No higher than the bottom of the plug opening

• | No lower than 15 mm (9/16 in) below the plug opening

5. If necessary, add to or replace the axle lubricant. Use synthetic 75W-90 gear lubricant (GM P/N 12378261), meeting GM specification 9986115, or equivalent.
6. If the vehicle has a limited slip differential, add 118 ml (4 fl oz) of limited slip differential additive (GM P/N 1052358), or equivalent.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

7. Install the rear axle housing drain plug.

Tighten
Tighten the rear axle housing drain plug to 35 N·m (26 lb ft).

8. Lower the vehicle.