Manual transmissions, transaxles, and differentials are big gear sets that don’t have pumps like automatic transmissions. They lubricate the gears by dipping down in the oil and slinging it all over the inside of the housing. Manual gears don’t usually require external cooling.
Filling a manual gearbox is easy to do, but sometimes hard to access. Make sure you’re able to locate and access your transmission before you begin. Be sure to recycle any used fluids properly.
1. RAISE AND SECURE THE CAR SAFELY.
Use a jack and safety stands to raise the car. Make sure the car is secure.
2. LOCATE THE FILL AND DRAIN PLUGS.
The fill plug may be located on the side or back of the transmission or differential and may be identified with the word “Fill”
The drain plug is usually located on the bottom of the housing
Some differentials do not have a drain plug, but are emptied when the gear set is removed from the differential, which usually requires pulling the axles. If this is the case with your car, better it’s better to leave this repair to a professional.
3. DRAIN THE FLUID.
It is not necessary to drain the fluid in the transmission unless it needs to be changed per the manufacturer’s recommendations. To do so, remove the plug with your wrench and allow the fluid to drain completely from the housing into an oil pan or bucket.
Place a filter, a piece of cheesecloth, or a clean rag between the pan and housing to collect any loose metal shavings or contamination. If you see a lot of metal shavings, have a professional inspect the transmission. After draining, reinstall the drain plug.
4. FILL THE HOUSING.
If the old fluid came out clean, remove the fill plug and begin filling the housing with new fluid. Getting a bottle into confined areas can be difficult. You can install a piece of hose to the end of your fill bottle or use an inexpensive fluid pump to help push the fluid into the housing.
5. APPLY SEALANT.
Once the fluid starts running out of the fill tube, apply a little thread sealant to the plug and re-install the