Going to be filling my loop soon and wondering what additive to use. Seems as tho general automotive coolant is being used. My question is are most people using Dex-Cool type stuff (orange/redish) or typical green glycol. Only reason im wondering is that typically the dexcool stuff is supposed to be better for cross contaminated metals. copper w/aluminum. Or are most of you not even using coolant? being an auto tech i have loads of this stuff layin around 5yr dexcool red stuff and 3 yr Green stuff.