Mazda Trucks 1987-1993 Repair Guide

Manual Transmission



API GL-4 or GL-5 80W-90 or 75W-90 gear lube is recommended.


  1. Clean the dirt away from the area of the filler plug.
  3. Jack the truck if necessary and support it on jackstands, make sure the vehicle is level.
  5. Remove the filler plug from the case. The filler plug is the one on the side of the case. Do not remove the plug from the bottom of the case unless you wish to drain the transmission.
  7. If lubricant flows from the area of the filler plug as it is removed, the level is satisfactory. If lubricant does not flow from the filler hole when the plug is removed, add enough of the specified lubricant to bring the level to the bottom of the filler hole with the truck in a level position.


Pickups and MPV

See Figures 1, 2 and 3

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Fig. Fig. 1: Fill to slightly below the filler port

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Fig. Fig. 2: Filler and drain plug locations-MPV

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Fig. Fig. 3: Filler and drain plug locations-Pickup

The same procedure is used for both 4-speed and 5-speed transmission, but note that the 5-speed transmissions have two filler plugs and two drain plugs. Thus, to drain the 5-speed, both drain plugs must be removed, and to fill it, both filler plugs must be removed. The truck should be parked on a level surface, and the transmission should be at normal operating temperature (oil hot).

  1. With the truck parked on a level surface (parking brake applied), place a pan of at least four quarts capacity under the transmission drain plug(s).
  3. Remove the filler plug(s) to provide a vent; this will speed the draining process.
  5. On the pickup, remove the drain plug(s) and allow the old oil to drain into the pan. On the MPV, remove plugs labeled "A'', "B'' and "C'' in the illustration. Apply upward pressure on the drain plug until you can pull it out and direct the fluid into the drain pan.
  7. Clean the drain plug(s) thoroughly and replace.On the pickup, tighten to 15-20 ft. lbs. (20-27 Nm), if you have a torque wrench handy; otherwise, just snug the plug or plugs in. Overtightening will strip the aluminum threads in the case. On the MPV, coat all plug threads with sealant and install them. Tighten plug "A'' to 29-43 ft. lbs. (39-58 Nm), plug "B'' and "D'' to 18-29 ft. lbs. (24-39 Nm).
  9. Add lubricant through the filler plug(s) until it comes right up to the edge of the filler hole. Use the recommended gear oil. It usually comes in a squeeze bottle with a nozzle attached to the cap, but you can use a squeeze bulb or suction gun for additions.
  11. Install the filler plug(s). Tightening torque is 15-20 ft. lbs. (20-27 Nm) for pickups; 18-29 ft. lbs. (24-39 Nm) for MPV. Check for leaks after the vehicle has been driven for a few miles.


Drain and refill the transmission daily if the vehicle has been operating in water. All you have to do is remove the drain plug which is located at the bottom of the transmission. Allow all the lubricant to run out before replacing the plug. Replace with the recommended gear oil. If you are experiencing hard shifting and the weather is very cold, use a lighter weight fluid in the transmission. If you don't have a pressure gun to install the oil, use a suction gun.