Answer: This necessary service will keep your transfer case working properly. Transfer cases contain fluid that lubricates all its moving parts. Whether you have an old four-wheel drive vehicle, which contains a transfer case that uses gears to supply the front driveshaft with torque, or a new four-wheel drive vehicle, which contains a transfer case that uses a chain to supply the front driveshaft with torque, there is a tremendous amount of heat and friction created in the transfer case. This heat and friction can contaminate the transfer case’s fluid. The fluid can also become contaminated by water entering the transfer case. In order to keep the transfer case working properly, the old fluid will be drained, and new fluid will be added. The gears and shafts will be inspected and tested during a transfer case service. The transfer case will also be inspected for any leaks or holes.