1996 Ford F150 Owner's Manual - Page 344

NOTE: Use of a transmission fluid other than specified could result in transmission malfunction and/or failure. Refer to "Adding automatic transmission fluid", "Refill capacities" and "lubricant specifications" for further information. Checking the Automatic Transmission Fluid It is preferable to check the transmission fluid level at normal operating temperature 150˚F-170˚F (66˚C-77˚C), after approximately 20 miles (32 km) of driving. However, if necessary, you can check the fluid level without having to drive 20 miles (32 km) to obtain a normal operating temperature if outside temperatures are above 50˚F (10˚C). NOTE: If the vehicle has been operated for an extended period at high speeds or in city traffic during hot weather, or pulling a trailer, the vehicle should be turned off for about 30 minutes to allow the fluid to cool before checking. With the vehicle on a level surface, start the engine and move the transmission shift selector through all of the gear ranges allowing sufficient time for each position to engage. Securely latch the transmission shift selector in the Park (P) position, fully set the parking brake and leave the engine running. NOTE: Vehicles equipped with the 4x4 option must have the 4x4 shift selector in any position other than neutral. 345