F-450 and F-550 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.
Refill with new rear axle lubricant every 160,000 km (100,000 miles) under normal driving conditions on all F-450 and F-550 commercial applications. For F-450 and F-550 trucks operated at or near maximum gross vehicle weights, the rear axle lubricant should be replaced every 80,000 km (50,000 miles).
In addition, this 50,000-mile schedule should be observed when the vehicles are operated, where noted, under the Special Operating Conditions.