Actually, water has a much better heat capacity than a glycol mix, but the heat transfer generally increases with some glycol. I only use propylene glycol (animal friendly in case of spills), and have never spilled any on the track (on the grass next to and on top of the armco, yes, on the track, no). So, it really depends on your cooling needs, radiator size/material, engine specific output, frontal area & air flow through the radiator, fan wattage, etc. On cars with reduced airflow, I've found some propylene glycol antifreeze to make enough of an improvement in heat transfer (not capacity) to let a marginal system survive. BTW, I've had an engine meltdown ice racing in minus 20 degree weather, so it does matter even in the cold!


Originally posted by ddewhurst:
Water has 2 1/2 times better heat transfer properities than glyco-based products.

Have Fun
David