I second the method posted by Kestas. The factory fill in My 99 Civic was in there for over 125k miles before I got around to it. I did the flush TWICE to keep the new fluid from turning dark. 4 bottles of 12oz/ea is plenty per flush. Fresh, it has the color of vegetable oil. After 125k miles, it was like cola. No diff in P/S behaviour. Just peace of mind i guess.