Evens coolant uses propylene glycol as the cooling fluid rather than the traditional ethylene glycol. Propylene glycol has three carbons and ethylene glycol has two carbons as the names imply. Both are very water soluble. The differences are slight except that propylene glycol is non-toxic whereas ethylene glycol is toxic if ingested. I imagine you know that normal antifreeze is dangerous around pets because it has a slightly sweet taste and animals will ingest it. I believe that you do not dilute Evens with water but use it neat. I'm not sure of the reason for that but it means you will have to use twice as much and the cost is pretty high. I really don't see any real advantage to using the stuff unless of course you own the company.
WaterWetter is something altogether different. It is essentially a detergent that lowers the interfacial tension of the coolant mixture and this allows better contact with the surfaces it is trying to cool. I have been using it for about ten years. My impression is that it works pretty well and will help cool the engine more effectively but I never ran a side by side test comparison.
