Sounds like hogwash to me. .
Source of Review
A few excerpts:
" Strangely, Redline’s own test results don’t square with their ad copy. Their technical literature only shows an eight degree Fahrenheit drop in a car with a 50/50 mix of water and coolant, and an eighteen degree Fahrenheit drop for a car running 100 percent water.
I used a VagCom system (reads sensor data directly from the ECU) for my tests. The pre-WaterWetter® installation delivered temperatures between 96 and 98 degrees centigrade (or 205 to 208 degrees Fahrenheit for the Americans). The post-installation temperature stayed steady at 96 degrees centigrade. Clearly, not the results advertised.
Other websites have tested WaterWetter® and also concluded that the overall decrease in coolant temperature is marginal. So WaterWetter®’s benefits either lie elsewhere (or nowhere). That assessment requires a certain level of trust with Redline products. In my experience, based on their
oil products, they deserve this trust. "
*** EDIT: I read a bit more and this stuff does get some good reviews from users on Amazon. Some of them were bikes and some were Corvettes and a mix of other cars. I guess for the price, its worth a shot.