Originally Posted by tabetha

Neat coolant in the case of Ethylene Glycol can eat away water passages, and anything else made of copper or aluminum, really nicely, even though it may(should) have biocede in it, it will eat the material.
Another thing to consider is that it is way less effecient as a coolant than say a 50/50 mix, as the water is used as a catalyst to help increase heat absorbtion into the medium/coolant.
tabetha