What are coolants? A coolant or an antifreeze as it is commonly referred to, is a liquid that helps regulate the vehicle engine temperatures during operation. Coolants serve relatively simple but important purposes in automotive and industrial applications - corrosion prevention, freeze and boil protection if required. But in a market of ever-increasing technologies, OEM requirements, and even colors, coolants can seem very complex, maybe even downright vexing. With this complexity comes a series of questions ranging from “what’s the difference between a red coolant and a green coolant?” or “what will happen if I mix the two?” to “is ethylene glycol the same as propylene glycol?” This article attempts to answer most of these and some other questions by breaking things down into bite-size chunks that are easy to understand. What makes a coolant? While a coolant, in general, can be a liquid, or another substance depending upon the application, but our focus is on...