In short, yes, it is highly recommended that anytime you change your coolant, you should flush the system. Water corrodes your system from the inside. Harmful impurities and contaminants can cause scaling and other forms of corrosion within the walls of the hoses, radiator, and water pump. Over time coolant can become contaminated, and additives can wear out. Flushing the system as directed is the best way to ensure your new coolant performs at its best and provides dependable results for best results, flush with Engine Ice Flush Treatment or an equivalent product.Corrosion often produces sludge, which, if left in the system, builds up and can cause rusting and ultimately leaks in the system.Scaling is a deposit formed on the inside of surfaces when the water is heated, and impurities precipitate or settle out. These deposits can build up and interfere with heat transfer or, in extreme cases, cause system and engine failure.