FORD 1999 Ranger - Manual (Page 167)

Correct fluid level
The transmission fluid should be checked at normal operating
temperatures 66°C-77°C (150°F-170°F) on a level surface. The normal
operating temperature can be reached after approximately 30 km (20
miles) of driving. However, you can check the fluid without driving if the
outside temperatures are above 10°C (50°F). If fluid is added at this
time, an overfill condition could result when the vehicle reaches normal
operating temperature.
The transmission fluid should be in
this range if at normal operating
temperature (66°C-77°C
[150°F-170°F]).
The transmission fluid should be in
this range if at room temperature
(10°C-35°C [50°F-95°F]).
High fluid level
Fluid levels above the safe range
may result in transmission failure.
An overfill condition of transmission
fluid may cause shift and/or
engagement concerns and/or
possible damage.
High fluid levels can be caused by an overheating condition.
Adjusting automatic transmission fluid levels
Before adding any fluid, make sure the correct type is used. The type of
fluid used is normally indicated on the dipstick and/or dipstick handle
and also in the Lubricant specifications section in the Capacities and
specifications chapter.
Use of a non-approved automatic transmission fluid may cause
internal transmission component damage.
If necessary, add fluid in 250 mL (1/2 pint) increments through the filler
tube until the level is correct.
If an overfill occurs, excess fluid
should be removed by a qualified
technician.
Maintenance and care
167