Usually the transmission filter is replaced when the transmission fluid is drained during routine service on an automobile. This is not the case with the Hyundai XG-350, however. The transmission filter on this vehicle is located deep inside the transmission and to change it, the transmission must be disassembled. This makes it impractical to service the filter during a routine service. Because the filter will not be replaced, changing the transmission fluid on a XG350 is a straightforward job that does not require much time.
Jack up the front of the XG350 and install the jack-stands under the frame of the vehicle. Make sure the car is level from side to side so the transmission fluid will drain properly. Slide a drain pan underneath the transmission and loosen the drain plug. Allow the fluid to drain and inspect the drain plug gasket to make sure it is intact and may be reused. If it is damaged, replace it. If it is in good shape, reinstall the plug after the fluid is drained.
Remove the drain pan from underneath the car. Lower the car to the ground by first jacking the car up and removing the jack-stands then lowering the jack. Estimate the amount of fluid in the drain pan, which is usually under two quarts. Remove the transmission dipstick under the hood of the car and install a funnel into the dipstick tube opening. Pour less than the estimated amount of fluid into the transmission. Start the car and allow it to warm up.
Wipe the dipstick clean with a shop rag then insert it into the dipstick tube and check the level of the fluid. Make sure the car is at operating temperature, the parking brake is set and the transmission is in neutral. The transmission is full when the fluid is at the full-when-hot mark on the dipstick. If it is low, add a little of the transmission fluid at a time until the proper level is reached, then test drive the car to make sure it shifts properly. Retest the fluid level. If it becomes overfull, it will be necessary to drain the excess fluid. It is also critical that the right level be reached when the car is hot and has been driven. This ensures fluid has circulated throughout the transmission.
