Ethylene Glycol antifreeze needs to have some water in the mix to work properly. It is neither a good coolant nor an effective antifreeze if it's used straight. Never run more than a 70% concentration of antifreeze, which has a freeze point of around 60 below zero F. Straight antifreeze without water mixed with it starts to get a little slushy at 13 degrees ABOVE zero. The standard 50/50 mix freezes at -37 degrees, and also is a good heat transfer medium. Unless you're running your truck somewhere like Fairbanks Alaska, there's not much need to run stronger than a 50/50 mix. Installing 2 gallons of straight antifreeze and topping the system off with water will result in a 50% mix, or slightly stronger. Any water you can drink will be fine in a cooling system. Distilled or demineralized water is ridiculously unnecessary.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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