Flushing the transmission fluid on a 700 R4 transmission is a highly recommended procedure. Most lube shops have a fully automated machine that can perform the task in only a few minutes. It's possible to do at home; however, the results will not be as thorough as the machine version. On the plus side, however, some new car manufacturers include the procedure outlined here in their service manuals, so it is a valid process.
Raise the hood of the car and place the drain pan directly underneath the transmission oil-cooler lines that are running to the radiator. Slightly loosen the bottom line with a flair nut wrench but do not completely remove the line from the radiator.
Start the car and let it idle. Fluid will drip at a fast rate from the fitting. If it is too loose, transmission fluid will spray around the engine compartment. It is better to start with the fitting fairly tight and loosen it accordingly until an ideal discharge rate is achieved.
Run the car until 7 or 8 qts. of fluid have discharged. The maximum capacity is nearly twelve quarts so this leaves a good safety margin. No gears are engaged during this process, so there is little chance of damaging the clutch plates or bands inside the transmission.
Tighten the bottom fitting and refill the transmission with fresh transmission fluid. Start the car and let it idle. Operate the gears then set the gear selector to park. Recheck the fluid level when the car is at operating temperature and adjust it until it reaches the "Full when hot" mark on the dipstick.
