GM Service Manual Online
For 1990-2009 cars only
  1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle.
  2. Ensure the vehicle is level.
  3. Inspect the rear axle for leaks. Repair as necessary.
  4. Clean the area around the rear axle fill plug.
  5. Remove the rear axle fill plug.
  6. Inspect the lubricant level.
  7. Specification
    The lubricant level should be between 0-10 mm (0-0.4 in) below the fill plug opening.

  8. If the level is low, add lubricant until the level is even with the bottom edge of the fill plug opening. Use the proper fluid. Refer to Fluid and Lubricant Recommendations.
  9. Caution: Refer to Fastener Caution in the Preface section.

  10. Install the rear axle fill plug.
  11. Tighten
    Tighten the rear axle fill plug to 33 N·m (24 lb ft).

  12. Lower the vehicle.