I have a 95 Windstar with 185K mi. and the PS pump was making noise at about 110K. I just removed the fluid in the reservoir and replaced it with a synthetic fluid. I then drove it for a few days and repeated the procedure once or twice. In all I used about a 32 oz bottle of synthetic PS fluid.Since then it hasn't made a noise in years. This may not be the most efficient way of doing it but it was the cleanest and easiest way with what appear to be good results.