If you're in the process of getting some new transmission fluid, you might've come across the term, ATF. It simply stands for 'automatic transmission fluid', which marks it as a transmission fluid that's been formulated and designed to work well with automatic transmissions. ATF's mixture and chemical makeup are very different, and in most cases, they can't be used with a manual transmission. Within an automatic gearbox, ATF functions to lubricate the many moving parts within your car's transmission. In so doing, it not only preserves the gearbox's performance but also ensures its longevity and reliable operation. Plus, ATF is used to cool down a transmission, just as how motor oil functions in a car's engine. Just make sure you pick the right type of ATF for your specific vehicle.