Coolant options

Water works best and claimed better by several additives in the auto parts that also provide anti-corrosion. Most run water because tracks mandate that, but don't let it freeze and crack your block. I use Evans Waterless in 6 of my 7 cars. It is a mixture of ethylene glycol and propylene glycol (per MSDS), which you might be able to do yourself (later is sold as Sierra Coolant). Cost $43/gal and no more corrosion or need to ever change if you don't lose it. Works good in my 1984 M-B because it has a slight heater core leak, so I run w/ the radiator cap loose so it builds no pressure to leak. Would replace the heater core except that is a 3-day job and the part costs $500. My thought is that if it cools OK today w/ Evans, that is "good enough" and will never change since no corrosion.