Just to be clear, I was NOT advocating nor would I ever suggest the use of pure water. I was demonstrating the most efficient "cooling" could only be attained by pure water. The additives in the cooling system are necessary for freeze protection, corrosion resistance and lubrication of pump parts (specifically pump seals). I don't run anything in my cooling system outside manufacturer recommendations simply because the enginerds designing the system covered all the bases for system requirements long term.