Power steering fluid and ATF are the same thing. As for replacement, I do mine every whenever I do brakes. The easiest way is to remove the lower return hose and put in in a jar. The return hose is the pipe clamped hose not the compression hose. Now with the car on jack stands turn the wheel all the way left, then all the way right. Do that about 3 times and then check the level of the resivior. Flush through atleast a quart. This not only removes the old fluid but also flushes the rack. Hope that helps.