Running and in Park . . .
From the 2000 F-150 Owner's Manual:
Automatic transmission fluid expands when warmed. To obtain an
accurate fluid check, drive the vehicle until it is at normal operating
temperature (approximately 30 km [20 miles]). If your vehicle has been
operated for an extended period at high speeds, in city traffic during hot
weather or pulling a trailer, the vehicle should be turned off for about 30
minutes to allow fluid to cool before checking.
1. Drive the vehicle 30 km (20 miles) or until it reaches normal operating
2. Park the vehicle on a level surface and engage the parking brake.
3. With the parking brake engaged and your foot on the brake pedal,
start the engine and move the gearshift lever through all of the gear
ranges. Allow sufficient time for each gear to engage.
4. Latch the gearshift lever in P (Park) and leave the engine running.
5. Remove the dipstick, wiping it clean with a clean, dry lint free rag. If
necessary, refer to Identifying components in the engine compartment
in this chapter for the location of the dipstick.
6. Install the dipstick making sure it is fully seated in the filler tube.
7. Remove the dipstick and inspect the fluid level. The fluid should be in
the designated area for normal operating temperature or ambient