Actually... redline water wetter has been tested in competition conditions by racers, and they swear by it. On the racetrack, despite having a working high-pressure radiator cap and a looser thermostat, excessive heat produced by long periods of high-revving can overload an engine's cooling capacity. Water Wetter keeps the water in the coolant from boiling over once this point has been reached (and, believe you me, drive hard enough, like I do, and you can definitely reach it).

Mike Kojima swears by it... and I trust the guy... like, man... he's the dude...

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As for new engines running really hot... it's crazy... issues with tuning the Focus TDCi for racing includes the fact that it runs maybe ten to twenty degrees hotter (in terms of coolant temps) than anything else. That's why it's got a waterless system. If you tried to use water in the TDCi's coolant tank... kablooey.