Coolant comes in a variety of colors and there are a lot of different brands for you to choose from. But why is that? Are the colors random or do they actually mean something? Can you mix coolant colors or should you stick to the color that your car currently uses?
Don’t worry, you’re not alone. I was once as confused as you are, but I intend to help in this post. This article will answer your question about mixing coolant colors, and everything you need to know about it. Use this table of contents to find the information you need:
How The Cooling System Works
For you curious cats out there, we’ll discuss how your car’s cooling system works and what role the coolant plays. Of course, if you already know how it works, then feel free to skip this section.
Modern cars use liquid cooling, a cooling system that relies on liquids to disperse heat from the engine. Of course, the system doesn’t just spray water onto the engine, it’s a little more complicated than that. Here are all the major components of your car’s cooling system:
- Water pump.
- Coolant temperature sensor.
- Radiator and radiator fan.
- Reservoir tank.
- Pressure cap.
Here’s how the system works: when you turn on the engine, the thermostat will open a bypass valve and close its main valve. This forces the coolant to flow back to the engine, and this helps the engine get to operating temperature quickly.
Once the coolant and engine reach a certain temperature—usually about 180°F—the thermostat will open its main valve. This allows the coolant to circulate into the radiator, where the radiator fins and fan will disperse heat from the coolant.
Afterward, the coolant exits the radiator and is pumped by the water pump back into the engine. The now-cooled coolant then can carry heat away from the engine, and back into the radiator via a set of hoses where it can cool down again.
This is a high-pressure system, where pressure increases along with the temperature, and the coolant essentially increases in volume. This is why it’s necessary to have a pressure cap to prevent it from bursting. Additionally, there’s a reservoir or an overflow tank that stores excess coolant. After the engine cools down, the coolant will travel back into the main system from the tank.
Antifreeze VS Coolant
Fairly simple, no? It’s one of the few components in your car where the inner workings are fairly easy to grasp. One thing you might be curious about is the difference between antifreeze and coolant. As some of your friends or mechanic may refer to it as antifreeze rather than coolant.
Antifreeze is technically a glycol-based fluid that, as the name suggests, prevents freezing. However, the name is a little misleading, as antifreeze actually freezes at around -5°F, whereas a 50/50 coolant and water mixture will freeze at -35°F. So, the antifreeze will actually freeze before the coolant does.
However, if you use a 70/30 mix of coolant and antifreeze, this will drop the freezing point to a very chilly -84°F. Note that some coolant comes premixed with antifreeze, and when your mechanic says antifreeze, it’s likely they’re referring to this type of coolant.
As you can guess, the purpose is to prevent the coolant from freezing for car owners in freezing regions. Needless to say, your car won’t work properly if it freezes. The best case scenario is that it will take an eternity to warm up, but in the worst case scenario, it may seize the engine and you’ll need an expensive engine rebuild.
Can You Mix Coolant Colors
So, now to answer your main question, can you mix coolant colors? The short answer is yes, as long as it’s the same type of coolant, you can safely mix the coolant in your car.
Some coolant manufacturers now even make universal coolants that can mix with any coolant colors safely. Does that mean the color doesn’t mean anything then? Well, this is where it gets a little complicated.
In the olden days, coolant colors indicate the type of additives that the coolant uses. These additives are useful to prevent corrosion inside the cooling system, and you can tell the type by the color of the coolant.
Additionally, the additive type also determines when you need to change the coolant. These additives and the coolant break down at different rates, hence the different change intervals. There are three types of additives, and here’s a list of coolant colors and what type of additives they use:
Early coolant use IAT or Inorganic Additive Technology, which uses silicates for the inhibitor. And in the olden days, they come in green. You’ll find these coolants mostly in older cars, but some modern cars may use this as well—it depends on the design of their cooling system.
IAT coolants aren’t necessarily worse than other types; they cool the engine just fine. But they have the shortest interval change, and the car will usually need a coolant change every 24,000 miles.
After IAT, came the OAT-type coolant or Organic Acid Technology. As the name suggests, this uses organic acids as the base for the coolant. Early OAT coolant all came in the orange color, and this is commonly used in GM, Saab, and VW cars. Cars with this type of coolant typically require a coolant change every 60,000 miles or so.
The next type of coolant is HOAT which stands for Hybrid Organic Acid Type. This type of coolant uses a mix of silicates and organic acids, and the most common color for this type is red. Manufacturers often refer to them as Extended Life Coolants (ELC) as they can go up to 100,000 miles or five years before needing a change.
Turquoise coolant is quite rare, but certain cars use this such as BMW and MINI. It’s also based on HOAT technology.
Blue coolant uses P-HOAT technology, which is a blend of phosphates and organic acids. This is currently one of the most common types of coolant, as many carmakers use this for their cars. This includes Toyota, Nissan, Honda, and Hyundai amongst others.
The change interval varies, and sometimes coolant makers will claim it will last over 150,000 miles before needing a coolant change.
Pink coolant is a bit rarer, but it uses the same P-HOAT technology as blue coolant. The color usually depends on the manufacturer.
Can You Mix Coolant Colors: Should You?
So, as you can see there are a total of four different coolant types and technology. As mentioned, the colors indicate the coolant type in the olden days. However, these days the color isn’t a reliable indicator of the coolant type.
Perhaps, the question you should be asking is “SHOULD you mix coolant colors?” Well, we always like to be on the safe side on these things, and we’ll say no. It’s better to be on the safe side, and use the coolant that your car is currently using.
Mixing coolants can result in the coolant transforming into a gel-like substance. Needless to say, this will prevent flow and your cooling system won’t work properly.
Best to be on the safe side of things to prevent major damage to the engine. However, if you’ve verified that the coolant you’re about to use is the same type as your current coolant, then you can safely mix them.
How About Mixing It With Water?
Yes, you can. But only use distilled water, or better yet, de-ionized water. Do not use tap water or mineral drinking water as they have minerals that can form deposits inside the cooling system. This will result in blockages, and reduce the efficiency of the system. As a result, your engine will overheat, and may even cause damage.
Coolant has to be mixed with water, as water is an efficient heat conductor and helps to cool down the engine. However, water has a lower boiling point, which is why you need to mix it with coolant. Note that some coolant already comes premixed with water, in which case you don’t need to mix it before putting it into the system.
If you notice your coolant level is low and you don’t have coolant on hand, you can top it up with distilled water to prevent overheating issues. But for optimum performance and protection, you should always use coolant.
Maintaining Your Cooling System
So, we’ve established that while you can safely mix coolant colors as long as they’re the same type, it’s better to be on the safe side and not do that. Unless you’re in a pinch, you should use the same coolant you’re already using.
Now, cooling system repairs are quite expensive. And here are the things you can do to maintain it:
Can You Mix Coolant Colors Maintenance Tips #1: Use The Right Coolant
Needless to say, it’s important to use the right coolant recommended by your car manufacturer. There have been many reports where DIY owners use a different type of coolant and their car doesn’t work quite right.
You can find the coolant type you need in your service manual. If it’s not there, check with your car’s dealership or a trusted auto repair shop. You can also find this information in owner’s forums, they’re usually very helpful.
Using the manufacturer’s coolant is a safe bet, and you can buy them from your dealer. But these are usually more expensive, so you can buy coolant from any of the major aftermarket brands instead, such as Prestone or Valvoline. As long as you’ve ensured it’s the correct type for your car, you’ll be fine.
Oh, a couple more things: always use new coolant. Coolants attract dust and dirt easily, and old coolant that hasn’t been stored properly would easily get contaminated.
Finally, the system is pressurized and coolant volume changes with the temperature. Always ensure that coolant isn’t below the minimum level or exceeds the maximum marker. Both of these can cause overheating issues, and possibly damage to the system.
Can You Mix Coolant Colors Maintenance Tips #2: Tighten The Radiator Cap
As mentioned, the cooling system is a high-pressure system, and therefore it needs a pressure cap to keep the system in check while it’s operating. Most cars have the pressure cap on the radiator, but some may have it on the reservoir tank instead.
In any case, you’ll want to ensure that you’ve tightened them properly. The cap regulates the pressure inside the cooling system, and a properly working cap will keep your cooling system in good shape for a long time.
Additionally, a loose pressure cap can allow air to get inside the system. This results in pockets of air bubbles in the system, which reduces its efficiency. And it can also cause premature corrosion inside the system.
Can You Mix Coolant Colors Maintenance Tips #3: Clean The Radiator Fins
Radiators have fins that extend from the radiator which dissipates heat from the coolant and onto the atmosphere. If the fins get dirty or damaged/bent, it can reduce the radiator’s efficiency in removing heat from the coolant.
So, cleaning the radiator can help both with the system’s efficiency, and extend the radiator’s lifespan. That being said, cleaning the radiator can be a bit tricky as you often need to remove the front bumper to gain access. But here’s a quick guide:
You should also clean the condenser while you’re at it. The condenser is part of your car’s A/C system and looks similar to a radiator, cleaning it will help maintain your A/C system. You can learn more about the condenser and how to clean it here.
Note that cleaning the radiator fins is somewhat optional. Carmakers do recommend it once a year, but the more important maintenance you should do is flushing the cooling system:
Can You Mix Coolant Colors Maintenance Tips #4 Flush The Cooling System
Flushing the cooling system involves draining old coolant from the system, refilling it with a cleaning fluid, then running the engine for about 10 minutes to let the fluid circulate.
Afterward, you’ll need to refill it with new coolant as the old one would’ve been contaminated. We’ll let ChrisFix show you how to do it:
You’ll need to repeat the steps several times if you want to clean it thoroughly, and you should. Doing it halfway will cause dirt and debris to flow freely inside the system which could damage components and do more harm than good. Something I learned the hard way with my old Mitsubishi.
If you don’t have the time to do this yourself, most repair shops will charge around $200 for a cooling system flush. Be sure to shop around and ask for recommendations, just to make sure that the shop can do a good flush job. You can learn more in our guide to radiator flushing costs.
Can You Mix Coolant Colors Maintenance Tips #5: Don’t Ignore Leaks
This goes without saying, but you shouldn’t ignore leaks in your cooling system no matter how small. Some leaks may be so small that it barely affects the coolant level, but ignoring them can damage the engine and cooling system in the long run.
Leaks can happen internally or externally. External leaks mean you’ll see coolant leaking out of the system, while internal leaks mean that coolant is leaking into the engine. In the case of the latter, you’ll often notice white smoke coming out of the exhaust pipe. This is usually caused by a blown head gasket.
In any case, both can be detrimental to your engine and shouldn’t be ignored. Our guide to finding leaks in your car will help you solve your problems.
Can You Mix Coolant Colors FAQ
We’re sure you have plenty more questions about coolants, so here are some answers you might find useful:
What Does Coolant Do
Coolant circulates through passageways in the engine to carry away heat that the engine produces via conduction. It then goes into the radiator to cool down and then recirculates back into the engine to repeat the process. This keeps your engine at optimum operating temperature and prevents overheating and damage.
Is Antifreeze Coolant
Antifreeze is technically a glycol-based fluid. You can buy antifreeze separately, but it’s often already mixed into the coolant. When people say antifreeze, they’re often referring to coolant that’s been premixed with antifreeze.
What Is Antifreeze Used For
Antifreeze, as the name suggests, is to prevent liquid from freezing. Antifreeze itself freezes at -5 degrees Fahrenheit. But when you mix it with coolant (it usually comes premixed) then it will lower the freezing point to around -84 degrees Fahrenheit. Very helpful if you live in cold regions where the winter gets very cold.
Where Does Antifreeze Go
Antifreeze goes into your car’s cooling system. To add antifreeze, locate your car’s coolant reservoir. Wait for the engine to cool down, and then add the antifreeze into the reservoir. Follow the instructions on how much antifreeze you should add, and do not exceed the maximum marker on the reservoir tank.
What Coolant Does My Car Need
You’ll need to check your service manual for this. If you can’t find it, search for the information online, owner’s forums are usually very helpful. And you can also inquire about this from your car’s dealer to find the correct coolant.
What Color Is Coolant
Coolant comes in many different colors, including blue, pink, orange, and the two most common colors are red and blue.
How Long Does Coolant Last In A Car
This depends on the coolant type. IAT-type coolant which is usually green typically has the shortest lifespan of about 24,000 miles. OAT-type coolant is often orange in color and can last up to about 60,000 miles. Meanwhile, HOAT-type coolant is usually red in color and can last up to about 100,000 miles or more. You should check with your service manual to find out which coolant you should be using and the change interval for your car.
Where To Buy Coolant
You can buy coolant from any number of places: your dealership, local auto parts store, grocery stores such as Walmart, and even online on Amazon. You can buy from any of them, but the important thing is to buy the correct coolant for your car.
Can You Mix Coolant Colors: In Conclusion…
In conclusion, while you can safely mix coolant colors, it’s best that you don’t. Best check what type of coolant your car uses, and then use that for your car. You can often find this information in the service manual. And if it says you should use red coolant—and your car currently already uses red coolant—then you should stick with that.
If you’re in a pinch, then you can safely mix coolant colors as long as you ensure that it’s the same type of coolant. As mentioned, coolant colors nowadays don’t always indicate the coolant type. As long as you’ve verified that it’s the same type, then it will be safe to mix them.
Perhaps, the safer option is to mix it with distilled water if you’re in an emergency. If you’re on the road and noticed that the temperature is a little high and the cooling system needs a top-up but don’t have access to the correct coolant, you can safely mix it with distilled water.
Water freezes and boils more easily than the coolant, but it can still efficiently cool down the engine. Just make sure to use distilled water to prevent damage to the system. Distilled water works great if you’re in a pinch, but you should address the issue afterward.
The cooling system is a closed-loop system, so you’re not supposed to lose any significant amount of coolant. If you do, then it means you have a leak somewhere, either internally or externally. You’ll need to find it and fix it as soon as possible before it causes overheating and damage to the engine.
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