Ford F series 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.
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).
RWARNING
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