For a Manual Transmission (likely AX-5 or T-176):
* Fluid Type: Use GL-4 rated gear oil. The specific weight (e.g., 80W-90, 75W-90) might be specified in your owner's manual, but 80W-90 is a common and safe choice. Always double-check your owner's manual for the manufacturer's recommendation.
* Tools: You'll need a drain pan, socket wrench (size will depend on your drain plug), fill plug wrench (again, size depends on the Jeep), funnel, and new transmission fluid. Jack and jack stands are highly recommended for safety.
* Procedure:
1. Safety First: Ensure the Jeep is parked on a level surface, securely supported by jack stands, and the emergency brake is engaged.
2. Locate Drain Plug: This is typically on the bottom of the transmission case. It might be a bolt or a plug.
3. Drain Fluid: Carefully remove the drain plug, allowing the fluid to drain completely into your drain pan. Note the fluid's condition (color, smell, presence of metal particles).
4. Locate Fill Plug: This is usually on the side of the transmission case, often higher than the drain plug.
5. Replace Drain Plug: Once the fluid has stopped draining, replace the drain plug, tightening it securely (but don't overtighten).
6. Fill Transmission: Using a funnel, add new transmission fluid through the fill plug hole. Check your owner's manual for the correct amount. You'll likely need to add more than what drained out. The fill plug should be level with the transmission case when the transmission is full.
7. Check Fluid Level: This is often done by removing the fill plug; fluid should be just below the fill hole. Alternatively, some use a dipstick (though less common on manual transmissions).
8. Replace Fill Plug: Securely tighten the fill plug.
9. Lower Jeep: Carefully lower the Jeep from the jack stands.
10. Test Drive: Take a short test drive to ensure everything is functioning correctly.
For an Automatic Transmission (likely AW-4 or Chrysler 3-speed):
* Fluid Type: Use the type of ATF (Automatic Transmission Fluid) specified in your owner's manual. This is crucial as using the wrong fluid can damage the transmission. Common types include Dexron II or III, but the manual is the final authority.
* Tools: You'll need a drain pan, socket wrenches (to remove the pan), a torque wrench (to reinstall the pan), new transmission pan gasket, funnel, and the correct ATF. Jack and jack stands are necessary.
* Procedure: This is more involved and often requires removing the transmission pan. It's *strongly* recommended to consult a repair manual specific to your Jeep's transmission for detailed instructions. Simply draining and refilling as you would a manual transmission is not sufficient. You'll need to replace the filter as well, typically located inside the pan.
Important Considerations:
* Owner's Manual: Always consult your 1989 Jeep Wrangler owner's manual for the specific fluid type and capacity recommendations.
* Repair Manual: For an automatic transmission, or if you're uncomfortable working on your transmission, a repair manual is highly recommended. These manuals provide detailed step-by-step instructions with diagrams.
* Professional Help: If you are not comfortable performing this task yourself, take your Jeep to a qualified mechanic. Improperly changing your transmission fluid can cause significant damage.
This information is for general guidance only. Always prioritize safety and consult your owner's manual and/or a repair manual before attempting any automotive repair.
