arathol, doesn't matter which manual you will read, the coolant mix hasn't changed much over the years. Coolant is already mixed with water. In fact coolant is somewhere between 30% to 60% of the mix in the car, the rest is water. Also there is a thing called deionized water which is free of minerals and is perfect for this case.Nothing wrong? Its not about freezing, its about boiling over. This engine runs very close to the boiling point of water, so it needs proper coolant mix to keep from overheating. The proper mix raises the boiling point of the coolant to where it will not boil over. One good overheat might cause significant damage.
Water also has lots of contaminant minerals that can corrode and scale up the inside of the cooling system, eventually clogging it up.
When all else fails, RTFM.
I agree, but I will modify it a little. Never put PLAIN water in the coolant tank/radiator, no matter how little the amount. Get into the habit of using the proper mix of anti-freeze and filtered/condensed water. Each time that water is added to anti-freeze it dilutes it, changing the freeze/boiling points. It is very easy to forget that you added a little water to the coolant the last time it was low, so you add a little water again and before you know it, your coolant mix is way off from what is recommended in the owners manual. Also, with an unbalanced mix of coolant in the engine/radiator, rust and sludge will develop a lot more quickly.Read your owners manual.
You don't put water in the coolant tank either.