What kind of oil is used in a fluid drive?

In a fluid drive system, such as those found in certain automatic transmissions, a specialized Transmission Fluid is typically used. This fluid is designed to provide lubrication, cooling, and hydraulic pressure to facilitate the operation of the fluid coupling and other components. It often contains additives to enhance performance, reduce wear, and prevent oxidation. Common types include Dexron or Mercon fluids, but specific requirements can vary based on the manufacturer and design of the system.