FORD 2012 F-550 v.1 - Manual (Page 407)

Type B
If an overfill occurs, excess fluid should be removed by a qualified
technician.
An overfill condition of transmission fluid may cause shift and/or
engagement concerns and/or possible damage.
Do not use supplemental transmission fluid additives, treatments or
cleaning agents. The use of these materials may affect transmission
operation and result in damage to internal transmission components.
TRANSFER CASE FLUID (IF EQUIPPED)
1. Clean the filler plug.
2. Remove the filler plug and
inspect the fluid level.
Maintenance and Specifications
407
2012 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)