Why do all the bottles of radiator flush say to use with water? like prestons super radiator flush says to drain all the fluid replace with water then add the cleaning agent why is this?

 

best to remove the radiator and flush it. at least flush separately from the rest of the cooling system. that way your not pushing stuff into the engine or heater core. i believe the antifreeze negates the cleaning solution.

 

hm and thats the thing i need it to get the whole system because something is plugged. getting it flushed by a shop tomorrow and they suggested that i put cleaner in it and drive on it for a day or so before bringing it in...... its kinda cold out and i did not want to blow the radiator or worse crack block by putting water in it

 

When you refill it, ideally you should be using distilled water, to reduce impurities which could leave deposits.