why flush?
There is a block drain under the alternator and a heat exchanger drain an the bottom rear. Open them both, allow to drain, run a fresh water hose into the tank and run the engine for an extended period (disc the raw water belt if not in the water) with the drains open. Permanent anti freeze should be 50% mix in the fresh water side of the cooling system. How often do you change the coolant in your car? I have been a mechanic for over 30 years and I NEVER change anti freeze. The additives to "flush" out the system may destroy the fresh water pump seal and should not be used unless there has been severe contamination.
