Under normal conditions, the manufacturer feels that manual transmission
fluid should not need to be changed. However, if the truck 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 of highway
driving. Fluid which is warmed to normal operating temperature will flow faster,
drain more completely and remove more contaminants from the housing.
- Drive the vehicle to assure the fluid is at normal operating temperature.
- 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.
- 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.
NOTE: To insure 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.
- Remove the fill plug, then the drain plug and washer, allowing the transmission
fluid to drain out.
NOTE: The transmission drain plug may have a square receiver
which is designed to accept a 3⁄8 in.
driver such as a ratchet or extension.
- Once the transmission has drained sufficiently, install the drain plug,
with a new washer, until secure. Tighten the drain plug to 30–42 ft.
lbs. (40–58 Nm).
- Fill the transmission with the specified amount and type of oil through
the hole until the level reaches the bottom of the hole.
- Install the filler plug, with a new washer, once you are finished.
- Remove the jackstands and carefully lower the vehicle.
