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I hear you talk on your radio show about coolant exchanges using a 50/50 mixture of distilled water and antifreeze. My question is: 1) Why do you need to exchange your antifreeze instead of just draining and filling? 2) Why do you need to use distilled water instead of just tap water? The reason I am asking this question is that shops have told me that draining and filling is all I need to do to my cooling system. They say using a 50/50 mixture is correct but distilled water is not needed. Who do I believe?

I understand why you are puzzled with answers that you been given about your cooling system. So let me answer your questions so that you will be able to explain to your shop why a coolant exchange is needed, as well as why to use distilled water in the 50/50 mix. So here goes……. A coolant exchange will change 96 to 98% of your total amount of coolant you have in your cooling system. An average car holds between 3.5 to 4.5 gallons of coolant in the block, hoses, heater core, radiator etc. The only way to get the old coolant out is to “exercise” the coolant. This can only be accomplished by the engine running at operating temperature. To do this you must have a coolant exchange machine. Let me explain how this machine works. As the coolant heats up the thermostat opens and the “old” coolant goes into the machine. The new coolant from the machine goes into the radiator helping push the old coolant into the machine. It will only push the “old” hot coolant into the machine. This is how you replace 96 to 98% of the old coolant. This insures that cooling system is properly maintained. Just draining and filling will only change about 35 to 45% of the old coolant. It would take 3 to 5 “drain and fills” to do the same job that a cooling exchange machine can do in about an hour. Saving YOU time and money! Now to the distilled water versus tap water debate… We all learned in 5th grade science that pure water contains Hydrogen and Oxygen, that’s all. Tap water on the other hand has in its chemical makeup, sodium, calcium, chloride, fluoride, magnesium and a plethora of other trace minerals. These extra trace chemicals/minerals help deplete the antifreeze’s reserve alkalinity. This lowers the pH value in the cars cooling system in weeks. These extra “goodies” in the tap water will cause your radiator to clog up and the metal to in the cooling system to slowly dissolve away. So common sense tells you that distilled water is better for your cars cooling system than tap water. I know that automotive engineers have told me that their organization “The Society of Automotive Engineers” (SAE) recommends distilled water as well. Tap water is a big NO NO!


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