When servicing a transmission, there are several important things to keep in mind. You will need the vehicle VIN to help identify what type and quantity of transmission fluid you will need, as well as the right filter and gasket set. There are a huge variety of fluids, both standard and synthetic. Many manufacturers use several different fluids, depending on the model. Many fluids are not available in an aftermarket brand. When draining the old fluid and removing the transmission pan, make sure to check for metal or debris, to help identify and eliminate other problems.