Evans coolants are unique from all other propylene glycol-based antifreezes in that they are to be run without any water dilution - PURE propylene glycol along with whatever waterpump seal lube chemistry Evans has concocted. (which is why I labled Evans a true "coolant" instead of merely "antifreeze") Propylene glycol has significantly less heat exchange capacity when compared to water, and still somewhat less when compared to ethylene glycol. But, it also won't boil. (OK, it really will boil, but only at some ungodly high temperature - well outside the range an engine will be subject to if the cooling system is well maintained.) Boiling coolant opens up gas pockets that could subject bare metal to corrosion and leaving hot spots at critical points (often in the area around the exhaust valve seats - the last place you want a hot spot) in the cooling system. Once a person gets past the seemingly contradictory thermo-dynamics that an engine can operate safely at a somewhat higher temperature than "normal" and yet still not supply sufficient heat through the heater core on a northeastern winter morning, the Evans approach makes sense. But at $25.00-$30.00 per gallon, it's a hard sell for many - me, too.
Ironically, there was a time in the distant past (the '50s) when Rolls Royce and Bentley cars were filled at the factory in Crewe, England with 100% Prestone. In most of the world, new owners were told by the automotive press to dilute that to 50% immediately. Funny, that those crazy Limeys might've really been onto something . . .
