Rear Axle Lubrication

Rear axle lube quantities must be replaced every 100,000 miles (Except F-Super Duty), or if the axle has been submerged in water. Otherwise lube should not be checked unless a leak is suspected or repair required. F-Super Duty rear axle lube quantities must be replaced every 30,000 miles unless synthetic oil is used. Super Duty vehicles are NOT equipped with synthetic oil from the factory.