Ford Super Duty Owner's Manual page 416

Scheduled Maintenance
Operating in dusty or sandy conditions such as unpaved or
Every 50000 miles Change rear axle fluid (F-450/550 only).
(80000 km)
Every 60000 miles Change transfer case fluid (4WD vehicles).
(96000 km)
*
Vehicles equipped with dual rear wheels should rotate the front wheels
when specified; rear wheels only if unusual wear is noted.
Inspect frequently, Inspect steering linkage, ball joints and U-joints,
service as required Lubricate if equipped with grease fittings.
Replace engine air filter.
Every 5000 miles Change engine oil and filter.
(8000 km) or
Inspect the wheels and related components for
six months
abnormal noise, wear, looseness or drag.
Rotate tires
tread depth.
Every 30000 miles Replace front wheel bearing grease and grease
(48000 km) seals if non-sealed bearings are used.
Every 50000 miles Change rear axle fluid (F-450/550 only).
(80000 km)
Every 60000 miles Change transfer case fluid (4WD vehicles).
(96000 km)
*
Vehicles equipped with dual rear wheels should rotate the front wheels
when specified; rear wheels only if unusual wear is noted.
Exclusive use of E85 (flex fuel vehicles only)
Every oil change If ran exclusively on E85, fill the fuel tank full
interval with regular unleaded fuel.
2013 F-250/350/450/550 (f23)
Owners Guide gf, 3rd Printing, December 2012
USA (fus)
dusty roads
Off-road operation
*
, inspect tires for wear and measure
415