FORD 2001 F-550 v.2 - Manual (Page 217)

Checking and adding transfer case fluid (if equipped)
1. Clean the filler plug.
2. Remove the filler plug and
inspect the fluid level.
3. Add only enough fluid through
the filler opening so that the fluid
level is at the bottom of the
opening.
Use only fluid that meets Ford specifications. Refer to the Capacities
and specifications chapter.
AIR FILTER MAINTENANCE
Refer to the scheduled maintenance guide for the appropriate intervals
for changing the air filter element.
When changing the air filter element, use only the Motorcraft air filter
element listed. Refer to Motorcraft Part Numbers.
Note: Do not start your engine with the air cleaner removed and do not
remove it while the engine is running.
Maintenance and care
217