The Difference Between Green and Orange Antifreeze

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.

FAQ

Can I use a universal coolant if I don’t know which antifreeze is required?

Probably, but make sure to check your owner’s manual first, to make sure it’s approved.

“Universal coolants should only be used temporarily because engines are designed to use specific types of coolant,” says John Vorisek, founder at Repair Surge. “Each type has its own chemical makeup, and long-term use of a universal coolant can damage the internal parts of the engine.

Tim Rodifer technical director for Mr. Transmission also warns about using universal coolant. “While universal coolants are designed to mix with most types, they aren’t compatible with every system,” he says. “Using the wrong antifreeze can cause corrosion and scaling in the radiator, potentially leading to overheating and damage to other components like the heater core.

How can I tell if my antifreeze is old or degraded?

Use a test kit, or just look for visual signs like a change in color, a cloudy texture or particles or sediment. A burnt smell can also be a clue.

“Fresh antifreeze is usually bright green, pink, or orange with a fluorescent look,” says Rodifer. “Degraded antifreeze can also lose its sweet smell, fail a hydrometer test, or contribute to overheating issues.”

Also, check your owners manual to see if you’re overdue for a coolant change.

“Keep in mind the intervals manufacturers recommend should be cut in half based on what is called severe driving conditions,” says Frank Scandura, owner of Frank’s European Service. “Most manufacturers will recommend service intervals at normal driving conditions, when in reality most people drive under severe operating conditions.”

About the Experts

• John Vorisek is founder at Repair Surge, which he started in 2003 to provide factory-authorized automotive service data to help owners and independent auto repair facilities diagnose vehicles.
• Tim Rodifer is technical director for the Moran Family of automotive franchisors, including Mr. Transmission/Milex Complete Auto Care where he worked for more than two decades.
• Frank Scandura is owner of Frank’s European Service in Las Vegas, Nevada, has 45 years of automotive experience and has written dozens of articles for AutoTechIQ, a resource for car owners who want to educate themselves about car issues and find trusted repair shops nearby.

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