The Difference Between Green and Orange Antifreeze

What's the difference between different colors of antifreeze? Should different colors of coolant be mixed? Find out here.

green antifreeze poured into coolant systemShutterstock/ Papzi555

Why is Coolant Different Colors?

Were you paying attention the last time you topped off the antifreeze in your vehicle? Do you remember what color it was? While all antifreeze has the same end goal (mixing with water to regulate engines during extreme temperatures), the different colors can sometimes tell you a lot about what specifically went into your antifreeze’s formula.

Keep in mind, though, that as coolant formulas have developed over the years and new technologies have been introduced to the market, the clearly defined differences between coolant colors have been blurred. The best way to know what kind of coolant belongs in your vehicle is to read through its owner’s manual and match that information to what’s on the label of the coolant, not the color. If you need further clarification or help deciding on a coolant, contact the dealership you purchased the vehicle from.

Why is Antifreeze Green?

If antifreeze is green, that probably means it was made from an older formula that uses something called Inorganic Additive Technology. Green antifreeze is made with special tweaks to the formula specifically to help prevent the corrosion of metals in a vehicle’s cooling system. That older formula is typically meant for vehicles made before the year 2000, which were built with more steel and copper components than modern vehicles. Most manufacturers recommend changing IAT antifreeze every 36,000 miles or three years. Here’s a guide to flushing antifreeze from your cooling system.

Why is Antifreeze Orange?

If antifreeze is orange, it was most likely made with a more modern formula based around what are known as Organic Acid Technologies. Towards the end of the 1990’s, vehicle manufacturers began to use more aluminum and nylon in cooling systems. That meant the anti-corrosion elements in the green antifreeze formula, specifically meant to prevent corroding in metals, were no longer effective against these new components. Coolant manufacturers updated the formula to combat corrosion in new materials and changed the color to orange. While OAT antifreeze is designed to last much longer than IAT antifreeze, it’s still a good idea to have your orange coolant checked about every 50,000 miles. Want to test your coolant? Here’s how to do it with a multimeter.

Can You Mix Orange and Green Antifreeze?

It’s never a good idea to mix two different colors or types of antifreeze. Mixing two formulas won’t cause any dangerous reactions or explosions, but it could turn your coolant into a sludgy chemical mixture that won’t be able to flow properly through your cooling system. Coolant needs to be fluid in order to do its job, and a thick coolant could clog up the cooling systems, leading to other potential issues in your vehicle’s engine. The bottom line? Don’t mix different colors of antifreeze.

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