Ford Super Duty Owner's Manual

agesilaus wrote:

My differential (front/rear) fluid is still the factory lube so it probably needs to be changed although I believe the manual says it's doesn't ever need to be changed.

Really? Mine was 125,000 I believe. Like the transmission and transfer cases. If you have a 2012 I'd double check that since that's what I have.

Manual wrote:
Every 15000 miles
(24000 km)
Inspect engine and secondary cooling system
concentration (freeze-point protection), additive
strength (corrosion inhibitor), coolant level and hoses. 2
Every 22500 miles
(36000 km)
Replace engine- and frame-mounted fuel filters. 3
Every 30000 miles
(48000 km)
Replace climate-controlled seat filter (if equipped).
At 45000 miles
(72000 km)
Replace air inlet foam filter. 4
Every 60000 miles
(96000 km)
Replace front wheel bearing grease and grease seal if
non-sealed bearings are used (2WD vehicles).
At 90000 miles
(144000 km)
Inspect accessory drive belt(s). 5
At 100000 miles
(160000 km)
Change rear axle fluid (Dana axles. Refer to Special
operating conditions). 6
At 105000 miles
(168000 km)
Change engine coolant. and secondary coolant. 7
Every
150000 miles
(240000 km)
Change automatic transmission fluid and filter. Consult
dealer for requirements.
Change front axle fluid (4WD vehicle).
Change transfer case fluid (4WD vehicles).
Replace accessory drive belt(s) if not replaced within
the last 100000 miles (160000 km).
Replace front wheel bearings and seals if non-sealed
bearings are used (2WD vehicles).

If you have a Dana rear axle which comes on a DRW F350 you have to change the fluid but on a F250/F350 SRW comes with the Ford rear axle which doesn't require a fluid change. I'm going to need to have my serpentine belt replaced so I will probably have the Ford dealer change the fluids in the front and rear axles. Having said that I usually inspect them for leaks when a change the engine oil and both of them are bone dry.

I'm on my second Super Duty with ~200k miles with the factory lube in the axles.