it is very important to flush the powersteering fluid on fords. there are many ways of doing it, the most common way is to remove the reutrn line, plug the resivoir and run the motor turning the wheel back and forth while putting in fresh fluid. you know youre done when the fluid coming out the return hose is the same color as the fluid you are putting in. i would suggest using a synthetic ATF like mobil 1 or Redline for the fluid. not servicing the power steering is a major contributing factor to the dreaded ford power steering groan.