"O" - Off-Road Operation

Every 15,000 miles - Lubricate 4X4 front hub needle bearings (F Super Duty)

Every 30,000 miles - Change automatic transmission fluid.

Every 60,000 miles - Change transfer case fluid.

As required - Replace cabin air filter.

As required - Inspect and lubricate U-joints.

As required - Inspect and lubricate steering linkage ball joints with zerk fitings.