Ford Super Duty Owner's Manual page 309

308
Correct Fluid Level
For vehicles equipped with 5-speed transmissions, the fluid should be
checked at normal operating temperature 150°F-170°F (66°C-77°C) on a
level surface. For vehicles equipped with 6-speed transmissions, the fluid
should be checked at normal operating temperature 196°F-216°F
(91°C-102°C) on a level surface. The normal operating temperature can
be reached after approximately 20 miles (30 km) of driving.
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.
2013 F-250/350/450/550 (f23)
Owners Guide gf, 1st Printing
USA (fus)
Maintenance
Type A
Type B
Type A
Type B