Re: Coolant for Aluminum Radiator
I pretty much agree with all of the above... dexcool bad, prestone good, premix is a ripoff, use distilled water from the grocery store, cooling system needs pressure to work properly and avoid creating steam pockets in the heads.
Straight glycol has crappy heat transfer properties. It won't freeze, but you may overheat.
Thermostat temps are a religious discussion. Thermal efficiency vs volumetric efficiency. Volumetric wins for most SBCs (assuming you're goal is power). Some people say thermal wins on LSX's with plastic intakes and some form of cold air induction, but I haven't seen any dyno numbers to back that up.