Originally Posted by David M

Antifreeze has chemicals that reduce corrosion. Yes, pure water does hold more heat energy per volume than does ethylene glycol but you still need the chemicals in antifreeze. Your thermostat will more than compensate for the heat energy difference between the two. So you do not want to use pure distilled water for any length of time. Also, color has nothing to do with what you need.

You need G-05 or equivalent MB 325.0 ethylene-glycol based HOAT...Hybrid Organic Acid Technology. G-5 (HOAT) provides silicates that provide protection against aluminum corrosion. This provides protection for up to 150K miles... (I would change it sooner than that though). You do not want the additives to become depleted.