1997 Ford F250 Owner's Manual - Page 282

Checking the Automatic Transmission Fluid Transmission fluid should be checked at least twice a year. 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 (30 km) of driving. However, if necessary, you can check the fluid level without having to drive 20 miles (30 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 gearshift through all of the gear ranges allowing sufficient time for each position to engage. Securely latch the transmission gearshift in the P (Park) 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. RWARNING Your vehicle should not be driven if the fluid level is below the bottom hole on the dipstick and outside temperatures are above 50˚F (10˚C). 283