The first question you might have is what is the transmission? It is located behind the engine and is responsible for transferring the power from the engine into forward and reverse motion to the wheels. So when it breaks you're on the side of the road. So it is important to take care of this component. One of the best ways is changing the fluid and filter when needed. Common practice in the past was to remove the Transmission pan and replace the filter and what fluid came out with the pan. Problem being is that you may only replace 4-5 quarts out of the possible 15 quarts in the transmission. That's like only changing 1.5 quarts during a standard 5 quart oil change. So what happens is the old leftover transmission fluid soon mixes with the new and its dirty again. A complete Transmission flush replaces all the fluid and gives long term protection and reliability. As you may know Transmission repairs can be very expensive, so think of this service as a good investment or lets just call it preventative maintenance.