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.

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 tell you a lot about what specifically went into your antifreeze’s formula.

Why is antifreeze green?

If antifreeze is green, that 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. Changing your antifreeze is one of the things you should do to prep your car for the winter.

Why is antifreeze orange?

If antifreeze is orange, it was made with a more modern formula based around what is known as Organic Acid Technologies. Towards the end of the 1990s, 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. Don’t use the wrong antifreeze. it’s one of 10 dangerous and costly car mistakes.

Can you mix orange and green antifreeze?

It’s never a good idea to mix two different colors of antifreeze. Mixing the 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. Combining the two is something you’re doing to your car that mechanics wouldn’t.

The Family Handyman
Originally Published on The Family Handyman