FORD 2008 E-450 v.2 - Manual (Page 263)

Low fluid level
Do not drive the vehicle if the fluid level is at the bottom of the dipstick
and the ambient temperature is above 50°F (10°C).
Correct fluid level
The transmission fluid should be checked at normal operating temperature
150°F-170°F (66°C-77°C) on a level surface. The normal operating
temperature can be reached after approximately 20 miles (30 km) of
driving.
You can check the fluid without driving if the ambient temperature is
above 50°F (10°C). However, if fluid is added at this time, an overfill
condition could result when the vehicle reaches normal operating
temperature.
ADD COLD HOT DO NOT ADD
2008 Econoline (eco)
Owners Guide (post-2002-fmt)
USA (fus)
Maintenance and Specifications
263