The transmission unit of the car lies on the lubricants. The transmission uses a certain fluid which is made for lubricating its components. If you put the wrong type of fluid in the transmission or have a fluid leak, then the gears and other metal components of the car would heat up and cause problems in the entire system. If you want to check the condition of the transmission fluid in manual and automatic cars, then have a look at the given video which provides all the information in detail.