Ford Mustang 1994-1998 Repair Guide

Manual Transmission



The manual transmissions covered by this guide use Mercon® automatic transmission fluid for lubrication. DO NOT use improper fluids such as gear oil. Use of improper fluids could lead to leaks or transmission damage.


See Figure 1

The fluid level should be checked every six months or 6,000 miles (9,600 km), whichever comes first.

  1. Park the car on a level surface, turn the engine OFF , FIRMLY apply the parking brake and block the drive wheels.

Ground clearance may make access to the transmission filler plug impossible without raising and supporting the vehicle, BUT, if this is done, the car MUST be supported at four corners and level. If only the front or rear is supported, an improper fluid level will be indicated. If you are going to place the car on four jackstands, this might be the perfect opportunity to rotate the tires as well.

  1. Remove the filler plug from the side of the transmission case using a 3 / 8 in. drive ratchet and extension. The fluid level should be even with the bottom of the filler hole.

Click image to see an enlarged view

Fig. Fig. 1: The manual transmission filler/inspection plug is normally found on the middle-to-upper side of the housing

  1. If additional fluid is necessary, add it through the filler hole using a siphon pump or squeeze bottle.
  3. When you are finished, carefully install the filler plug, but DO NOT overtighten it and damage the housing.


See Figure 2

Under normal conditions, the manufacturer claims that manual transmission fluid should not need to be changed. However, if the car is driven in deep water (as high as the transmission casing), it is a good idea to replace the fluid. Little harm can come from a fluid change when you have just purchased a used vehicle, especially since the condition of the transmission fluid is usually not known.

If the fluid is to be drained, it is a good idea to warm the fluid first so it will flow better. This can be accomplished by 15-20 miles (24-32 km) of highway driving. Fluid which is warmed to normal operating temperature will flow faster, drain more completely and remove more contaminants from the housing.

  1. Drive the vehicle to ensure that the fluid is at normal operating temperature.
  3. Raise and support the vehicle securely on jackstands. Remember that the vehicle must be supported level (usually at four points) so the proper amount of fluid can be added.
  5. Place a drain pan under the transmission housing, below the drain plug. Remember that the fluid will likely flow with some force at first (arcing outward from the transmission), and will not just drip straight downward into the pan. Position the drain pan accordingly and move it more directly beneath the drain plug as the flow slows to a trickle.

Click image to see an enlarged view

Fig. Fig. 2: The transmission fluid is removed through the drain plug in the lower portion of the housing

To ensure that the fill plug is not frozen or rusted in place, remove it from the transmission BEFORE removing the drain plug. It would be unfortunate to drain all of your transmission fluid and then realize that the fill plug is stripped or frozen in place.

  1. Remove the fill plug, then the drain plug and allow the transmission fluid to drain out.

The transmission drain plug is usually a square receiver which is designed to accept a3/8in. driver, such as a ratchet or extension.

  1. Once the transmission has drained sufficiently, install the the drain plug until secure.
  3. Fill the transmission to the proper level with the required fluid.
  5. Reinstall the filler plug once you are finished.
  7. Remove the jackstands and carefully lower the vehicle.