For anyone who is curious as to how well this stuff works, I have some real numbers. Since I have my
ScanGauge set to show me the water temps, I figured I'd throw a bottle in and see what it did. The answer is effectively nothing. The claims they make on the bottle indicate that you won't see much temperature difference in a 50% coolant / 50% water mix and I'm here to tell you it's the truth. In the temps we've been having here lately (30s to 50s), the water temp never really gets over 202 while the car is moving. After adding the Water Wetter it still gets to 202 but it does tend to hover more around 200. So two degrees difference when you're moving. It doesn't seem to help much when the car is stationary.
At $9 per bottle, I don't think it's worth it unless you're running straight water. I can't do that in my climate, so in the future I won't be using the Water Wetter. Perhaps 50/50 mix of this and distilled water would work quite well, but it doesn't provide any antifreeze protection. It is supposed to provide some lubrication and anti-corrosion protection over plain water. Anyway, just thought you would be interested.
Water Wetter. 
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