Automotive transmissions benefit from the proper service. Unfortunately, many places try and push a very profitable up sell to include a transmission flush. A transmission flush does your vehicles transmission very little good and in some cases may even harm your vehicles transmission. With a proper transmission service your vehicle is first test driven, then the transmissions external components are inspected, as well as being checked for leaks. Most transmissions have a removable pan and an external filter. On these transmissions the pan is removed, the filter replaced, and the valve body bolts checked for torque. The pans normal sediment is cleaned along with the magnets that attract the normal metal particles., the transmission pan is reinstalled with the proper torque on the transmission pan bolts, and then the vehicle is refilled with transmission fluid and test driven again. Flushing a transmission is simply done by removing the transmission cooler line from the radiator, connecting it to the flushing machine, and then starting the engine. As the fluid runs out into the machine the same amount of transmission fluid is added. As most transmissions hold 8-12 quarts of fluid, when one quart is taken out one quart of new fluid is added to the remaining 8-12 quarts mixing as it circulates stirring up sediment further restricting the filter which can damage the transmission. Technical service bulletin 04-06-01-029E, GM warns dealerships against several flushing procedures, In regard to transmissions, GM issued the following Statement "The use of external transmission fluid exchange or flush machines is NOT recommended for the automatic transmission. Use of external machines to replace the fluid may affect the operation or the durability of the transmission. Transmission fluid should only be replaced by draining and refilling following the directions in SI. Refer to Automatic/Manual Transmission Fluid and Filter Replacement." Transmission failure is many times caused by slippage. Slippage is often caused by low pressure, such as a restricted filter. Fluid color is often used as a selling tool for a transmission flush. This is also very misleading as fluid colors vary on many of today's cars, trucks and SUV transmissions. Darkening of fluid over time is perfectly normal. Many of today's fluids are not as red as traditional transmission fluids have been. The exception would be transmission fluid that is black and/or has a burnt odor. This indicates that a problem has already occurred and is too late for service and repair is needed. A low skilled technician can hook up the fluid machine and while the transmission is being flushed may proceed with other work making for a very profitable service to the shop. As they do not have any inventory of filters or gaskets, and many times use a universal fluid as opposed to the vehicles specific fluid that many manufacturers have on todays cars, trucks, and SUV transmissions. Proper transmission service by an expert like Action Transmission Specialists can help extend the life of a transmission. Beware of the "wallet flush". If someone tries to sell a transmission flush to you just say "NO" and Get Traction, Call Action. Where quality counts.