The oil in the manual transmission should be checked every 6,000 miles and replaced every 18,000 miles (24,000 miles 1974 models, 25,000 miles 1975-77 models, and 30,000 miles 1978-82 models) or 24 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 GL-4 oil of the proper viscosity. Use SAE 80 oil in all models, except for 1974-82, which uses SAE 90 oil.
DRAIN & REFILL
The transmission oil should be replaced every 18,000 miles (1970-73), 24,000 miles (1974), 25,000 miles (1975-77), 30,000 miles (1978-82), or 24 months (all years), whichever occurs first.
- Park the car on a level surface and put on the parking brake.
- Remove the oil filler (upper) plug.
- Place a container, of a large enough capacity to catch all of the oil, under the drain (lower) plug. Use the proper size wrench to loosen the drain plug slowly, while maintaining a slight upward force to keep the oil from running out. Once the plug is removed, allow all of the oil to drain from the transmission.
- Install the drain plug and its gasket, if so equipped.
- Fill the transmission to capacity. (See the Capacities chart.) Use API grade GL4 SAE 80 oil on all 1970-73 passenger cars. Use SAE 90 in 1974-82 models. Be sure that the oil level reaches the bottom of the filler plug.
- Remember to install the filler plug when finished.