Tools and Materials You'll Need:
* New differential fluid: The correct type and quantity will depend on your rear axle. Check your owner's manual or a parts store using your Firebird's VIN. (Usually 75W-90 or 75W-140 gear oil)
* Drain pan: Large enough to catch the old fluid.
* Wrench(es): The correct size for your differential drain and fill plugs. These are usually 10mm or 11mm, but check beforehand.
* Torque wrench: Essential to properly tighten the drain and fill plugs to avoid leaks. (Look up the correct torque specs in a repair manual or online).
* Jack and jack stands: Never work under a car supported only by a jack.
* Wheel chocks: To secure the front wheels.
* Gloves: To protect your hands.
* Funnel: To avoid spilling new fluid.
* Rags or shop towels: For cleanup.
* Optional: Impact wrench Can make removing the drain plug easier.
Procedure:
1. Safety First: Park the car on a level surface, engage the parking brake, and chock the front wheels. Wear safety glasses.
2. Raise the Rear of the Car: Safely jack up the rear of the Firebird and securely support it on jack stands.
3. Locate the Differential: The differential is located in the rear axle housing.
4. Locate the Drain Plug: It's usually located at the bottom of the differential housing. It's often a simpler bolt-style plug compared to the fill plug.
5. Drain the Old Fluid: Carefully position the drain pan under the drain plug. Slowly loosen and remove the drain plug, letting the old fluid drain completely. This can take some time. Inspect the old fluid for any metal shavings or unusual discoloration.
6. Locate the Fill Plug: This is usually located on the side or top of the differential housing, often with a slightly different shape or size head than the drain plug.
7. Remove the Fill Plug: This allows you to check the fluid level. If you can't remove it easily, try loosening it. Sometimes it's stuck. If very stuck, use a penetrating oil the day before.
8. Reinstall the Drain Plug: Once the old fluid has completely drained, reinstall the drain plug, tightening it to the correct torque specification (consult a repair manual). Do not overtighten!
9. Add New Fluid: Using a funnel, carefully add the correct amount of new differential fluid. The quantity is usually specified in your owner's manual or on the bottle of new fluid. A good way to check the level is to add until fluid starts to come out of the fill hole. Then replace the fill plug
10. Reinstall the Fill Plug: Tighten the fill plug to the correct torque specification.
11. Lower the Car: Carefully lower the car to the ground using the jack.
12. Check for Leaks: Inspect the area around the drain and fill plugs for any leaks.
13. Dispose of Old Fluid Properly: Differential fluid is hazardous waste and should be disposed of properly according to local regulations. Many auto parts stores will accept used oil.
Important Considerations:
* Rear Axle Type: The exact location and type of plugs can vary slightly depending on the rear axle type in your 1980 Firebird.
* Torque Specifications: Using a torque wrench is crucial to prevent leaks and damage.
* Fluid Type: Using the incorrect fluid can damage your differential. Double-check your owner's manual or consult a parts professional.
This is a general guide. If you're uncomfortable performing this task yourself, it's best to take your Firebird to a qualified mechanic. Improperly performed differential fluid changes can lead to serious damage to your vehicle.
