Ford 1996 Aerostar Manual page 285

It is preferable to check the transmission fluid
level at normal operating temperature, after
approximately 20 miles (30 km) of driving.
However, if necessary, you can check the fluid
level without having to drive 20 miles 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.
Checking the Automatic Transmission
Fluid
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 P (Park)
position, fully set the parking brake and leave
the engine running.
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).
Wipe off the dipstick cap (located toward the
passenger's side of the engine), pull the dipstick
out and wipe the indicator end clean. Put the
dipstick back into the filler tube and make sure
it is fully seated. Pull the dipstick out and read
the fluid level.
RWARNING
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