so a week ago I did a flush and fill following the accepted procedure here on the forum using the mb approved zerex coolant , I added two gallons of 50/50 mix , brought the engine temperature up to normal and then topped the coolant bottle off with half a gallon of distilled water, everything checked out fine , coolant was at -34 degrees Fahrenheit , I checked it again yesterday and now it is only at -7 degrees Fahrenheit. with all of that my question is if I drain the coolant tank and refill with straight antifreeze should that be enough to bring it back to -34 and should I add a cooling system conditioner ? thanks in advance .