Vehicle engines require coolants to keep them from overheating. In the past, there was only one kind of coolant (anti-freeze) and that was the green liquid. Today, there are two: The green coolant and the orange colored coolant, which is also known as Dexcool. Let’s look at these more closely.
The green coolant is an inorganic additive technology (IAT). With this type of coolant, phosphates along with silicates are added to ethylene glycol. This helps to protect the metals that are in the vehicle’s cooling systems from becoming corroded. There are some IAT coolants that use propylene glycol instead of ethylene glycol.
The orange coolants are organic acid technologies (OAT). These were created for newer vehicles that had more nylon and aluminum parts in them. OAT coolants use organic acids in order to prevent corrosion.
Some people believe that they can mix the two. This is a mistake and can lead to expensive repairs. The two coolants should never be mixed together as they do not react well. When mixed together they can form a thick, jelly-like substance that can completely stop all coolant flow which can lead to overheating. As the coolant stops flowing, other problems can occur as well such as happens with radiators, water jackets, and even heater cores. The water pump may overheat and stop working. In severe cases, head gaskets can blow, and heads may warp. The engine itself will encounter major damage.
As you can see, mixing the two is not a good idea. If mixing happens, it is best to have the entire system flushed before driving the vehicle. This is the only way to be sure that the system is clean and not at risk. Failure to perform this flushing can, and often does, lead to engine failure and costly repairs. It is better to take care of the problem before it gets much worse.