Can You Mix Orange and Green Antifreeze?

What Is the Purpose of Antifreeze?

Before you learn why you shouldn’t mix orange and green antifreeze, let’s take a look at why your car needs coolant in the first place.

Antifreeze is a liquid that is added to a vehicle cooling system. This cooling system is designed to do two main functions. These functions include cooling your car’s engine when it reaches a certain temperature and keeping your engine block from freezing during colder months.

When your vehicle is in operation, antifreeze is constantly flowing back and forth from your radiator to your engine block. This keeps your car cool so that it doesn’t overheat while you are driving down the road.

On the other hand, when the outside temperature drops below freezing, the chemical properties in the coolant keep your engine from freezing up.


What if You’re in a Pinch?

If you’re stuck out in the middle of nowhere and n

If you’re stuck out in the middle of nowhere and need to top off your coolant to get where you’re going, you have better options than mixing the wrong types of anti-freeze. While mixing the anti-freeze might get you where you’re going without any problems, you’re taking a risk.

Instead, all you need to do is add some distilled water to top off your system. While diluting the system with more water lowers the boiling point and raises the freezing point, a system with only 10 percent anti-freeze and 90 percent water will still only have a freezing point of 26 degrees Fahrenheit.

So, as long as you’re not driving during a snowstorm, you should be alright. If you read that and thought – I want the lowest possible freezing point, so I’m going to add 100 anti-freeze and no water – you’re mistaken. Adding water actually lowers the freezing point and glycol – to a point. The ideal anti-freeze to water ratio is 60 percent anti-freeze and 40 percent water.

But if you’re in a pinch, add water – not a different kind of anti-freeze. Not only will you avoid problems, but you’ll have no problem getting where you’re going either.


It is not recommended to mix antifreeze of different brands and colors, but there are some situations in which you have to do this. It is important to know that, when mixing, the color is not an important factor, but the chemical composition of the antifreeze, you should mix only identical ones from identical antifreeze classes.

It is important to know that allowed combinations of different antifreeze types are just for emergency situations and it is not recommended to continue driving like this after that. Antifreeze in G11 class and G12 class, should not be mixed, because this can lead to serious engine damage and costly repairs.

Watch for signs of oil or rust

The color of healthy engine coolant is green (for ethylene glycol) or orange (for Dexcool). A rusty color indicates that the rust inhibitor in the coolant has broken down and it can no longer control rust and scale buildup. The system must be cleaned/flushed and a fresh 50/50 mix of coolant installed to restore integrity. A milky color indicates the presence of oil in the system. This is not good; it usually means that a head gasket, intake manifold, or transmission oil cooler is leaking oil or transmission fluid into the engine coolant. This is a deadly mix that will kill an engine or transmission in short order. Address the probleFrim immediately!

What Happens When You Mix Antifreeze Colors?

Green antifreeze and orange antifreeze are the two most common versions that you’re going to find on the market. Those other colors are specialized formulations, and most drivers will probably not need to worry about them. Green or orange should work in the cooling system of just about any vehicle on the market, so you don’t need to worry about whether or not you have a brand that was specifically made for your car.

The problem with green and orange antifreeze is that they do not work together. They were designed to function in different ways. Orange antifreeze is a long-life antifreeze. It has a different chemical makeup than green, and they cannot be used interchangeably unless you have flushed your cooling system ahead of time.

If you find your system running low on antifreeze, let’s say that you have green but it needs to be topped off about halfway, if you were to try to add orange to the system you would actually create a kind of gel. The anti-corrosion chemicals that have been added to the orange mixture to make it last longer, will react when you add it to orange antifreeze. The whole mixture thickens up into a jelly substance. 

When your coolant thickens up like this it’s not able to circulate properly and do its job. This can lead to your engine overheating, which in turn can leave you with a pretty expensive repair bill overall. 

The only thing that coolant needs to be mixed with in your radiator is water. Ironically, antifreeze is much more effective when you mix it properly in the 50/50 proportions with water. Even though it seems like perhaps they would have better temperature regulating properties if you used it undiluted, that’s not the case. The freezing point of antifreeze is not that much lower than water by itself, and it is extremely inefficient at protecting your car from overheating if you just use it in its natural state without diluting it. The water and antifreeze mix creates a better temperature control and chemical compound that either one is able to manage just on its own.

What features does orange antifreeze have?

The orange antifreeze is a G12 type. Its composition is based on ethylene glycol, water, and additives ( borates, nitrites, etc.), but additionally, they include compounds of carboxylic acids. They have a lifespan of up to 5 years and have a wide range of use.

What do the colors mean?

Coolant and antifreeze are available in different colors, from red, pink, orange, blue, yellow, and green. When it comes to antifreeze or coolant, you should know this: the color determines its chemical makeup.

The different colors may also mean each antifreeze or coolant has other properties of the liquid. For instance, orange and green antifreeze will keep your engine from freezing or overheating. Green engine coolants are perfect for pre-2000 models, older cars containing multiple steel and copper components. But you can use orange on those cars too. 

So, before buying a coolant brand, you need to know which color will be suitable for your car. Consult your manual, the manufacturer of your vehicle should specify their preferred coolant brand.

Can I mix green coolant with orange coolant?

This is one of those questions usually asked after the fact, and usually engine damage has already occurred. The green and orange coolants do not mix. When mixed together they form a gel-like substance that stops coolant flow, and consequently, the engine overheats. There are some coolants that claim compatibility with Dexcool, but I would rather err conservatively and add what the system is supposed to take rather than gamble. To guard against major engine failure, read on.

What are the primary ingredients in coolant or antifreeze?

In most coolants, the primary ingredients that you will find are either ethylene glycol (EG) or less toxic propylene glycol (PG).

EG is an organic compound that contains antifreeze formulations.

On the other hand, PG is a commonly used compound for oral, intravenous, topical pharmaceutical preparations or inhibitors.

Another substance in a coolant or antifreeze brand is a pH buffer responsible for maintaining the alkalinity of the solution and anti-corrosive compounds that prevent the wearing out of your engine.  

The most common antifreeze out there is Ethylene Glycol for older vehicles and is usually green.

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.

What Is The Deal With Antifreeze Color?

Green Antifreeze

Green engine coolants are designed for use in olde

Green engine coolants are designed for use in older cars (think pre-2000), ones that contain a lot of steel and copper components in the cooling system. To protect these metallic parts from rust and corrosion, Inorganic Additive Technology (IAT) gets added to the mix.

IAT is a mixture of various compounds such as phosphates and silicones, with either propylene glycol or ethylene glycol. If we lost you there, don’t feel bad.

Phosphates are derived from phosphoric acid and help soften water and remove oil and grease. Silicones, on the other hand, work as a metal sealant, protecting them from different chemicals, moisture, and general wear.

Propylene glycol and ethylene glycol are what keeps your engine from overheating.

Orange Antifreeze

And then we have orange antifreeze, which also def

And then we have orange antifreeze, which also defends against corrosion but instead of being geared towards older cars with lots of metal, it’s made for newer cars with more aluminum and nylon parts in the cooling system.

One of these acids is carboxylates, which inhibit the buildup of corrosion. The great thing about these is that they only affect metal surfaces. Meaning they will protect metallic parts without interfering with non-metallic ones.

This transition from steel and copper to aluminum and nylon started back in the 90s. Due to this change, GM introduced DexCool. DexCool is a type of coolant that uses a mix of different Organic Acid Technologies (OAT) to help to help inhibit the buildup of rust and corrosion.

The cons of orange coolant manifest when it begins to run low. When this happens, oxygen may invade the system, creating a buildup that can clog and damage internal components.

Thankfully, orange antifreeze should last as long as 5-years. Meaning so long as you remember to refill it, your engine should not experience any issues.

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.

Intimidated by automotive work? Here are 12 great tips for DIY mechanics.


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