E and F-450 and 550 Series Axle Maintenance
WARNING: This page is about a different car, the 2007 Ford Pickup, 2007 Ford F550 Super Duty, 2007 Ford F450 Super Duty, and 2007 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Replace rear axle lubricant every 100,000 miles under normal driving conditions on all E and F-450 and 550 series applications. For E and F-450 and 550 series vehicles operated at or near maximum Gross Vehicle Weights, the rear axle lubricant should be replaced every 50,000 miles.
In addition, the 50,000 mile schedule should be observed when the vehicles are operated under the Special Operating Conditions.