Rear Axle Lubrication

Rear axle lube quantities must be replaced every 15,000 miles (Except 3500 HD) on vehicles used for trailer towing or use in dusty conditions. Otherwise lube should be checked for condition and fluid level at each oil change. 3500 HD rear axle lube quantities must be replaced every 3,000 miles unless synthetic oil is used. 3500 HD vehicles are NOT equipped with synthetic oil from the factory.