Here's a general procedure, but proceed at your own risk and double-check with your manual:
1. Preparation:
* Safety First: Work on a level surface. Use jack stands, *never* rely solely on a jack. Wear safety glasses and gloves. Have plenty of rags or shop towels ready.
* Gather Supplies: New differential fluid (check your manual for the correct type and amount), a drain pan large enough to hold the old fluid, a wrench (likely 10mm or 12mm for the drain plug and 10mm, 12mm, or possibly a larger size for the fill plug – again, check your manual), and a funnel. A torque wrench is highly recommended for proper tightening of the plugs.
2. Locating the Drain and Fill Plugs:
The front differential is located towards the front of the vehicle, typically near the front axle. It's a relatively large casing. The drain plug is usually located at the very bottom of the differential housing. The fill plug is usually on the side, higher up than the drain plug. Find these plugs *before* you get under the vehicle. Your manual will show their location clearly.
3. Draining the Fluid:
* Position the Vehicle: Secure the vehicle on jack stands. Allow sufficient clearance to work underneath.
* Locate and Remove Drain Plug: Carefully position the drain pan under the drain plug. Use the appropriate wrench to carefully loosen and remove the drain plug. The fluid will be hot if the vehicle was recently driven, so be cautious. Let the fluid drain completely. This may take some time.
* Inspect the Fluid: Examine the old fluid for color, consistency, and the presence of metal particles. This can help identify potential problems within the differential.
4. Refilling the Differential:
* Locate and Remove Fill Plug: Use the appropriate wrench to loosen and remove the fill plug.
* Add New Fluid: Using a funnel, slowly add the correct amount of new differential fluid (check your owner's manual). The fill plug should be at or slightly above the bottom of the fill hole. You'll likely need to check fluid level as you add more. Once you can see it oozing out, you are close to full.
* Replace Fill Plug: Carefully reinstall the fill plug and tighten it to the correct torque specification (from your owner's manual). Over-tightening can strip the threads.
5. Replace Drain Plug:
* Replace and Tighten: Reinstall the drain plug and tighten it to the correct torque specification (from your owner's manual). Don't overtighten.
6. Lower the Vehicle: Carefully lower the vehicle from the jack stands.
7. Check for Leaks: Inspect the area around both plugs for any leaks.
Important Considerations:
* Fluid Type: Use the correct type and weight of gear oil specified in your owner's manual. Using the wrong fluid can damage your differential.
* Torque Specifications: Always use a torque wrench to tighten the drain and fill plugs to the correct specifications. Over-tightening can strip the threads, and under-tightening can lead to leaks.
* Professional Help: If you're uncomfortable performing this task yourself, it's best to take your Astro to a qualified mechanic.
This is general guidance; your 1995 Chevy Astro AWD may have some specific differences. Always refer to your owner's manual for detailed instructions and specifications. Improperly performing this task can damage your vehicle.
