Ray, it looks like a quart will replace the entire system, but by the time you mess around letting it flow out of the wheel valves you might use more than that. I always buy 2 quarts and if I don't use the second one I return it unopened. Getting rid of the old stuff is getting harder. WalMart will still take it down here. NAPA, too, but many other places no longer want it to recycle (probably because it's hard to recycle for them, too).