Yeah it does reduce the surface tension but has no effect on the thernodynamic properties of water. This might slightly improve flow rate and thus cooling rate but not a huge factor. I don't know what is exactly in wetter but they probably won't allow anything that you cannot put in your body (ie inert). NASCAR is doing this for example in its concrete pit stalls. They are now using soda syrup to make stalls sticky. If you want to raise the boiling point minus anti-freeze then jack the pressure up. The radiator is generally the weakest link here ................

Kitz