When a customer brings you a vehicle that needs a coolant change, what kind of coolant should you use? The type of coolant specified by the vehicle manufacturer? A universal or “all makes, all models” type of coolant? Or should you run the old coolant through a recycling machine and put it back in the system? All are valid options for servicing today’s vehicles, but the options are not without controversy.

Before Dex-Cool was introduced back in 1995, almost every domestically produced vehicle used a traditional “green” formula inorganic acid technology (IAT) coolant. The Japanese and European automakers had their own versions of this formula. But as far as the aftermarket was concerned, the same stuff worked just fine no matter what you poured it into. So in that respect, green coolant was essentially a universal all makes, all models type of coolant for its day.

Then things got complicated. GM specified its orange-colored Dex-Cool coolant, which used a totally different kind of additive package based on organic acid technology (OAT). Ford and Chrysler opted for a hybrid version (HOAT) formula that added silicates to increase aluminum protection. The Japanese and Europeans both developed their own OAT formulas, with the Japanese adding phosphates while the Europeans took out phosphates. Everybody decided to dye their coolants a different color, which only added to the confusio...