If you want to flush everything out, including the heater core I like to buy the prestone kit sold about everywhere. You end up splicing into ont of your heater lines (the one going into it) and hose clamp a "T" fitting into it to attach a garden hose. Open the rad cap, start the car up and turn on the hose. Makes a mess but run it till you see nothing but clean water come out of rad. Then shut it off, drain the water from rad and fill back up with 50/50 and you should be good. I am sure other people have other ways but this works for me.