Back in the 50's my grandfather ran water in his late 40's AD pickup. When the weather got cold he'd pour a bottle of rubbing alcohol in the radiator and throw an old quilt over the front of the hood and grille. It worked for years.....then bang, one year the block split down the side. Some stop leak and he drove it for another two or three years.
...those were the days.
I agree with redwing, depending on where you live, that a 50/50 mixture is in order and forget it.
To save money though I buy the concentrate and mix my own. Kind of like 2 gallons for the price of one.