I use the redline water wetter too. I can say it really makes a big difference in my vehicles over standard coolants.... but, I live in south Florida where it never gets below 40 degrees, so I run the water wetter with straight water, and, I do not use a thermostat. I run tunes on my vehicles designed around an approximate 130 degree engine operating temp. The biggest difference the water wetter makes ... compared to standard coolants, is how quickly it reacts to reject heat. On my Ram, the engine usually runs right around 132 degrees (have checked this using a digital thermometer) at normal ambient temps (75-85 degrees) when using only water wetter and water. However, when idling a lot, or driving is slow traffic, especially in hot weather, the temps usually spike up to around 150. With the redline and straight water, the temp will drop back to near 132 in approximately 2-3 blocks of cruising at 55 or greater. With most standard coolants, it can take as much as several miles to return to the normal temperature. So I'd say it's a great racing coolant, or perfect for someone like me who likes to supercool their vehicles for extended engine life. Although water wetter has water pump lubricants and anti corrosion additives, it does not protect from freezing, so you can only use it with straight water when temps will not get down to freezing if you run it on the street. I have found it makes only a degree or so of difference when used in vehicles with a stock thermostat and 50/50 antifreeze solutions, so if you're running a bone stock setup, probably not worth the $10 price.
Dave
