I've never seen any rigorous scientific tests that show Water Wetter or any other cooling system additive either reduce coolant temperature or boundary temperatures in systems that run an OEM recommended antifreeze within the OEM recommended concentration range.

For race cars that don't run antifreeze, some kind of corrosion preventative/water pump seal lubricant additive is called for, but that's a completely different application than a street legal car that sees either regular or occasional use and uses the OEM recommmended antifreeze and mixing ratio.

OEMs design cooling systems for the heat capacity and convective heat transfer characterisitcs of a 50/50 blend of ethylene glycol and water, which provides freeze protection down to -34F and boiling protection to 265F with a 15 psi cap. Then they test everywhere between the arctic and Death Valley.

Freeze protection down to -84F is available with a 70 percent glycol solution, but this concentration is usually not recommended unless you anticipate temperatures this low, and if it gets that cold you won't have to worry about the lower heat capacity than a 50/50 blend.

The vast majority of anecdotal evidence I've seen from those who have reported using cooling system additives is basically - "made no difference" and like I said, I've never seen any rigorous scientific tests that back up any of the performance claims by manufacturers or some users or these products.

Duke