GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Manual Transmission



The oil in the manual transmission should be checked at least every 6,000 miles for 1964-74 models or every 7,500 miles for all 1975-81 models.

  1. With the car parked on a level surface, remove the level/filler plug from the side of the transmission housing. If the plug cannot be accessed with the car parked, it may be raised and supported by 4 jackstands so that the vehicle is level. DO NOT support the vehicle using cinder blocks, as they may crumble without notice and drop the vehicle suddenly.
  3. If the lubricant begins to trickle out of the hole, there is enough and you need not go any further. Otherwise, carefully insert your finger (watch out for sharp threads) and check to see if the oil is up the edge of the hole.
  5. If not, add oil through the hole until the level is at the edge of the hole. Most gear lubricants come in a plastic squeeze bottle with a nozzle; making additions simple. Some lubricant manufacturers will supply a small hose and hand-pump with their oil to further ease this process. If necessary, you can also use a common kitchen baster to introduce the oil into the transmission housing. Use only standard GL-5 hypoid-type gear oil - SAE 80W or SAE 80W/90.
  7. Replace the filler plug and, if applicable, lower the vehicle to the ground.
  9. Block the drive wheels and set the parking brake, then run the engine and check for leaks.


There is no recommended interval for the manual transmission but it is always a good idea to change the fluid if you have purchased the car used or if it has been driven in water high enough to reach the axles.

  1. The oil must be hot before it is drained. Drive the car at highway speeds for 10-15 minutes or until the engine and transmission reach their normal operating temperatures.
  3. If necessary for access, raise the front of the vehicle and support it safely using jackstands.
  5. Clean the area surrounding the level/filler and drain plugs using a old rag. Remove the level/filler plug to provide a vent.
  7. Place a large container underneath the transmission and then remove the drain plug. Remember to use a rag to protect your hands and to apply slight pressure to the plug as it is unthreaded in order to keep the oil from flowing freely until the plug is fully withdrawn.
  9. Allow the oil to drain completely into the pan. Clean off the drain plug and replace it; carefully tighten it until it is just snug.
  11. Fill the transmission with the proper lubricant through the level/filler plug bore as detailed earlier in this section. Refer to the Capacities chart for the correct amount of lubricant.
  13. When the oil level is up to the edge of the filler hole, replace the filler plug.
  15. If raised, remove the jackstands and carefully lower the vehicle.
  17. Drive the car for a few minutes, stop, and check for any leaks.