water cooled

Ok guys.. Here's a WIP render of the carbon fibre pocket bike chassis I've been working on. I'm showing it here with a conventional CAG engine dropped in place, and rather conventional components as I've already had them modelled, but the chassis is going to be quite unique and will look much...

So, what coolant do you guys use for your race engines and why? (If you have compared coolants tell me whitch ones )