Simply put, the transmission transfers power from the engine to the wheels. It houses gears, clutches, solenoids and other components that select the proper gear for the operating conditions. For example, when you start driving, a lower gear provides more torque. As you pick up speed a higher gear reduces engine rpm to improve fuel economy. There are two primary types of transmissions, manual and automatic. A manual transmission requires the driver to engage the clutch and shift the gears while an automatic transmission shifts into the optimal gear on its own.
Automatic transmission fluid (ATF) is a lubricant formulated to protect your vehicle’s gears and clutch packs while enabling smooth, crisp shifts. Without it, the gears in your vehicle’s transmission would rapidly overheat and wear out. ATF also fights heat and functions as a hydraulic fluid, squeezing clutch packs together, and delivering the right frictional requirements for seamless engagement and disengagement of clutch plates.
While it doesn’t need to be changed as frequently as motor oil, over time transmission fluid oxidizes and becomes contaminated with particles and sludge. Ignoring your ATF for too long could leave you on the side of the road with expensive repairs. Change the fluid according to the maintenance guidelines in your owner’s manual. If you tow or haul frequently, your fluid will require more-frequent changes. It’s also a good idea to use a transmission flush with your fluid changes to help clean trapped deposits or sludge. Although some vehicles today use “filled-for-life” transmissions that theoretically never require a fluid change, it’s best to change fluid at least once during their lifetime or more if you haul or tow. Doing so may require purchasing a special tool and a service manual, but it’s usually possible.
Other automatic transmission designs include continuously variable transmissions (CVT) and dual clutch transmissions (DCT). A CVT uses a pair of computer-controlled variable-diameter pulleys and a belt or chain to provide unlimited gear ratios. Dual-clutch transmissions are typically used in high-performance cars. They are essentially two manual transmissions working in tandem. These transmissions shift more quickly and smoothly than normal automatic transmissions. Because of their unique designs, CVT and DCT designs require specially formulated CVT fluid and DCT fluid.
A good ATF protects gears and moving parts from wear, fights heat, delivers the proper frictional requirements and functions as a hydraulic fluid. Consult your owner’s manual or use our product lookup to find the right transmission fluid for your vehicle.