The transmission is the link between the engine and the wheels of your vehicle. The transmission plays a crucial role in vehicle performance and reliability, keeping engine output matched with speed and load conditions, whether you drive a manual, automatic, or semi-automatic. Because engines operate at high rotational speeds, the transmission reduces engine output speed and transmits torque through the differential, driveshaft, and wheels. As engine speed varies, the transmission switches between the gears that influence the amount of torque applied to the wheels.
Transmission fluid performs a variety of duties, depending on the type of transmission. The fluid acts as a cooling agent and protects the transmission by lubricating the internal gears, preventing corrosion and rust. In a manual transmission, clutches and gear shifts provide pressure and force—like engagement and disengagement. However, an automatic transmission uses the transmission fluid to provide these same operational functions of force and pressure.