The oil in the manual transmission should be checked every 15,000 miles (24,000 km) or 12 months, whichever occurs first.
To check the oil level, remove the transmission filler plug. This is always the upper plug, the lower plug being the drain.
The oil level should reach the bottom of the filler plug. If it is lower than this, add API grade multi-purpose gear oil GL-4 or GL-5 of the proper viscosity. Use SAE 75W-90 or 80W-90 oil in all models.
DRAIN & REFILL
Changing the fluid in a manual transmission is not necessary under normal operating conditions. However, the fluid levels should by checked at normal intervals. The only two ways to drain the oil from the transmission is by removing it and then turning the transmission on its side to drain or by using a suction pump and a tube, then use the pump to suck the transmission oil out. Then when refilling the transmission, the oil level should be even with the edge of the filler hole or within 1 / 4 inch (6mm) of the hole.