A good time to have it checked is when the engine oil is checked. Refer to the Maintenance Schedule to find out when to check and change your manual transmission fluid. See Scheduled Maintenance .

Check the fluid level only when your engine is off, the vehicle is parked on a level place, and the transmission is cool enough for you to rest your fingers on the transmission case.

To check the transmission fluid level, do the following:

1. Remove the filler plug.
2. Check to be sure that the lubricant level is up to the bottom of the fill opening. On heavy duty transmissions, an inch of oil level equals about one gallon of fluid.
3. If the fluid level is good, reinstall the plug and be sure it is fully seated. If the fluid level is low, add more fluid as described in the next steps. Refer to the Maintenance Schedule to determine what kind of fluid to use. See Part C: Recommended Fluids and Lubricants .

To add transmission fluid, do the following:

1. Remove the filler plug.
2. Add fluid at the filler plug hole. Add only enough fluid to bring the fluid level up to the bottom of the fill opening. Refer to the Maintenance Schedule to determine the proper fluid to use. See Part C: Recommended Fluids and Lubricants .
3. Reinstall the filler plug. Be sure the plug is fully seated.