Pouring coolant into a reservoir. You may know coolant colors, like purple, green, and blue, but there's another type of coolant called Hybrid Organic Acid Technology. Here's the lowdown on these super-protective family of coolants.

What Is OAT Coolant?

Chances are you already know a thing or two about coolant: that it’s super important for your engine, that the type you use matters … but do you know the differences beyond green, orange, and purple? What is OAT coolant? If you’re not sure about this one, settle in and find out why it’s worth knowing.

Cool It Already!

Coolant keeps your engine, er, cooler than it would be otherwise. Components inside the engine move fast and Car enginegenerate a lot of heat from friction, so coolant is absolutely necessary to keep things from wearing prematurely, getting stuck and broken, or ending up in an all-out haze of smoke and panic. Additionally, the chemical makeup of coolant prevents it from freezing in cold conditions and aids in fighting corrosion.

Color Coordination

If you’re paying attention, you’ll notice there are different colors of coolant: green, orange, and purple. You might have heard the conventional wisdom not to mix them, but the truth runs much deeper than that. What you actually want to avoid mixing is the different chemical compositions. The first coolant was Inorganic Acid Technology (IAT). It’s good for a while (around 30,000 miles), but eventually becomes too acidic and has to be changed. Some older cars still use it. Next was Organic Acid Technology or OAT coolant. OAT utilizes additives to significantly increase time between system flushes, but it does have slightly reduced anti-corrosive properties. Nonetheless, many manufacturers use it in modern vehicles due to its long lifespan.

Hot OATs

There is also a third type of coolant called Hybrid Organic Acid Technology, or HOAT. This is a derivative of OAT coolant, but has more anti-corrosive properties. It’s important not to mix OAT, HOAT, and IAT for the reasons mentioned earlier, but how do you know when each is appropriate? The answer is in your owner’s manual. Never rely on color alone as coolants are dyed and the colors are not standardized across the industry. Mixing them can greatly reduce lifespan and gunk up your system.

Always double check to see whether you need OAT, HOAT, or IAT coolant, and never take a changeover into your own hands, because a simple flush isn’t enough to replace one type for another. And remember to let your engine cool before opening any radiator or reservoir caps or you could suffer burn injuries.

Check out all the chemical & lubricant products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on what is OAT coolant, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Blair Lampe.

about author

Blair Lampe

Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter.  In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.

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