1. Gather your materials. You will need:
* New gearbox oil (SAE 75W-85, API GL-4 or GL-5)
* A funnel
* A 17mm wrench
* A rag
2. Prepare your car. Park your car on a level surface and turn off the engine. Allow the engine to cool down completely. Engage the parking brake.
3. Locate the gearbox oil drain plug. The drain plug is located on the bottom of the gearbox, near the front of the car. It is a 17mm bolt.
4. Place a drain pan under the drain plug. This will catch the old gearbox oil.
5. Loosen the drain plug. Use the 17mm wrench to loosen the drain plug. Be careful not to drop the bolt into the drain pan.
6. Allow the old gearbox oil to drain. Allow all of the old gearbox oil to drain out of the gearbox. This may take a few minutes.
7. Replace the drain plug. Once all of the old gearbox oil has drained out, replace the drain plug. Tighten the plug until it is snug.
8. Locate the gearbox oil filler plug. The filler plug is located on the top of the gearbox, near the rear of the car. It is a 17mm bolt.
9. Remove the filler plug. Use the 17mm wrench to remove the filler plug.
10. Insert the funnel into the filler hole. Insert the funnel into the filler hole.
11. Add new gearbox oil. Add new gearbox oil to the gearbox until the oil level reaches the bottom of the filler hole.
12. Replace the filler plug. Once you have added the correct amount of gearbox oil, replace the filler plug. Tighten the plug until it is snug.
13. Check the gearbox oil level. Start the engine and let it run for a few minutes. Then, turn off the engine and check the gearbox oil level again. The oil level should be between the "MIN" and "MAX" marks on the dipstick.
14. Top up the gearbox oil if necessary. If the gearbox oil level is low, add more oil until it reaches the correct level.
