It's not hard to do, just tedious. You'll need a quart or three of ATF. Remove the old fluid from the reservoir first; you can buy pumps for bleeding brakes that will work. A turkey baster works fine also. Top off the reservoir with new ATF. Turn the wheel from one stop to the other a couple times to cycle the fluid. Repeat until reservoir fluid looks like new.
I also use Mobil 1 SATF (new it's a dark translucent red)
