Ford 2014 F-Series Super Duty Owner's Manual page 130

Extensive idling or low-speed driving for long distances, as in heavy commercial use
Every 30000 miles (48000
km)
Every 60000 miles (96000
km)
*
Vehicles equipped with dual rear wheels should rotate the front wheels when specified;
rear wheels only if unusual wear is noted.
Operating in dusty or sandy conditions (such as unpaved or dusty roads)
Inspect frequently, service
as required
Every 5000 miles (8000
km)
Every 5000 miles (8000
km) or six months
Every 30000 miles (48000
km)
Every 50000 miles (80000
km)
*
Vehicles equipped with dual rear wheels should rotate the front wheels when specified;
rear wheels only if unusual wear is noted.
Exceptions
There are several exceptions to the Normal
Schedule:
Normal vehicle axle maintenance: Rear
axles and power take-off units with
synthetic fluid and light-duty trucks
equipped with Ford-design axles are
lubricated for life; do not check or change
fluid unless a leak is suspected, service is
required or the assembly has been
submerged in water. During long periods
Motorhome (TY3) , enUSA
Scheduled Maintenance
(such as delivery, taxi, patrol car or livery)
Replace front wheel bearing grease and grease seals if
non-sealed bearings are used.
Replace spark plugs.
Replace engine air filter.
Inspect the wheels and related components for abnormal
noise, wear, looseness or drag.
*
Rotate tires , inspect tires for wear and measure tread
depth.
Change engine oil and filter.
Inspect and lubricate U-joints.
Replace front wheel bearing grease and grease seals if
non-sealed bearings are used.
Change rear axle fluid.
127
of trailer towing with outside temperatures
above 70°F (21°C) and at wide-open
throttle for long periods above 45 mph (72
km/h), change non-synthetic rear axle fluid
every 3000 miles (4800 kilometers) or
three months, whichever comes first. This
interval can be waived if the axle is filled
with 75W140 synthetic gear fluid meeting