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Keeping your engine cool or warm, depending on the climate, is vital to the longevity of your car. Too cold, and your car won’t start, but too warm, and it’ll stop working in a very dramatic fashion. Keeping your engine at a perfect operating temperature is your car’s cooling system, which employs the use of antifreeze. Antifreeze is not, however, coolant, though many believe it to be.

To better understand your car’s cooling system, what part antifreeze and coolant play in keeping your car humming along, as well as the difference between the two, Car Bibles’ icy-cool editors put together this perfect companion to your car’s manual. So scroll along, get educated, and learn all about your car’s antifreeze and cooling system.

Ed. Note: This post was refreshed with new and updated text on 6/24/2021 by Tony Markovich.

What Is Antifreeze?

Simply stated, antifreeze is concentrated ethylene glycol and silica, though the levels of each will depend on the manufacturer. Antifreeze and coolant, however, aren’t interchangeable terms. 

Two containers of Fram antifreeze on top of a '60s Dodge Charger engine block.
It’s always a good idea to prepare for the future and buy more antifreeze than you need. – Image: Hank O’Hop

What Is Coolant?

Coolant is created when either the customer or manufacturer mixes concentrated antifreeze solution with good ol’ H2O. This mixture then goes into your cooling system via the radiator. Make sure it’s distilled water, though, as regular tap water could contain contaminants the could affect the cooling system.

How Does Antifreeze Work?

When combined with water, the antifreeze/water solution (coolant) helps regulate an internal combustion engine’s temperature to keep it from both overheating and being too cold to operate. 

What’s the Difference Between Coolant and Antifreeze?

As mentioned above, Antifreeze is the concentrated solution of ethylene glycol and silica, while coolant is that solution combined with water. This mixture is what regulates your engine’s temperature. 

Antifreeze and Coolant Explained
Sometimes the coolant reservoir is located near the radiator, other times it’s separate. – Image: Hank O’Hop

The Job: Performing an Antifreeze/Coolant Replacement 

With this guide, you will learn how to remove coolant from your engine and cooling system and how to replace the coolant without leaving any air in the loop.

The Safety Brief

Working around and underneath a vehicle is inherently dangerous. Be sure to protect your skin and eyes with nitrile or mechanic gloves and a set of safety glasses. It’s also crucial to use jack stands any time you are lifting up a vehicle to access underside parts.

If you have pets or animals anywhere near where you work on your car, you’ll want to be especially careful with antifreeze because creatures will often try to taste it. But as you might guess, the stuff is toxic even when it’s diluted with water, so clean up spills and keep containers of the stuff sealed.

The Tools & Parts You Need

Below, we have created a checklist for the equipment and items you will need for checking and adjusting your front wheel alignment.

Tools

Other Products

A close-up of a radiator cap on a '60s Dodge Charger.
Note the warning on the cap: DO NOT OPEN HOT. – Image: Hank O’Hop

How To Remove and Replace Coolant/Antifreeze

Before we begin, please heed this warning: Never attempt to open your radiator cap when the engine is hot.

  1. Park your car on a level surface, turn the heater temperature all the way up, and let it run for a minute.
  2. Turn the vehicle off and let it cool down.
  3. If needed to access drainage plugs, use a jack to lift the car up and insert jack stands.
  4. Remove the radiator cap.
  5. Place a drain pan underneath the radiator drain plug/petcock and unscrew the drain plug to release the coolant into the drain pan.
  6. Screw the radiator drain plug/petcock back in.
  7. If your car has a drain plug on the engine block, move the drain pan underneath that and remove it to drain more coolant.
  8. Use a torque wrench to crew the engine block plug back in to the manufacturer-specified torque number.
  9. Remove the coolant overflow reservoir and dump out the coolant or use a liquid transfer pump to remove the coolant.
  10. With a funnel, fill the reservoir with premixed coolant or your mixture of antifreeze and distilled water. Be careful not to fill over the max line. Close the reservoir cap.
  11. Pour the coolant in the drain pan into old coolant bottles for transfer and proper disposal at your local recycling center. Do not pour coolant down the drain or on the ground.
  12. Check your owner’s manual to determine how much coolant your system takes. Then, with a funnel, fill the radiator with coolant. 
  13. Squeeze the radiator hoses to help push any air out of the system.
  14. Leave the radiator cap off and turn the vehicle on, with the heat temp all the way up. Run the car for 10-30 minutes to allow any trapped air to work its way out of the system. 
  15. If the coolant level goes down, add more coolant. 
  16. Put the cap back on the radiator and you’re done!

Technically, this is a simple coolant replacement, not a total flush. A full flush includes running fluid through the system to give it a more complete clean and rinse. For that, you will need a running spigot with a hose, a few clamps, and a coolant flush kit. To perform a simple flush of the radiator only, you could run distilled water through it and let it drain out before you replace your coolant.

Car Bibles‘ Antifreeze Glossary

Welcome to Bible school!

Thermostat

Thermostats are used to monitor and regulate temperatures, both in climate control systems and in engine control systems. 

Radiator

Radiators are devices in vehicles that take in hot coolant liquid and use a series of fins and grates to dissipate heat out into the air. The coolant then circulates back into the engine, where it gathers more heat for the radiator to cool.

Coolant Temperature Sensor

A coolant temperature sensor (CTS) is a small device that reads the cooling system’s coolant temperature by measuring and responding to changes in electrical resistance.

Head Gasket

Your head gasket can either be some type of squeezed-on polymer or pseudo-fabric liner that sits between an engine’s head(s) and block. Its job is to maintain pressure and keep the engine’s disparate fluids away from one another by sealing off various compartments and fluid lines. It can sometimes fail, and coolant can leak into the cylinders and cause a blown head gasket, which almost certainly destroys the engine.

The Antifreeze and Coolant Questionnaire

Car Bibles answers your burning questions!

Q. What do the different colors of coolant mean?

A. Colors used to determine how the coolant was manufactured, with blue and green coolant signaling Inorganic Additive Technology as the primary base, while orange signaled Organic Acid Technology, the new kid on the block. You can also look at antifreeze manufacture websites like this one for some guidance on the significance of different colors.

Practically speaking, the main thing you need to know about the color of coolant is that your car probably calls for a specific one, and ideally, you shouldn’t mix different colors together. There are a few different ways to figure out what color coolant your car needs:

  • Check the owner’s manual
  • Check the label on the jug of coolant you’re looking at and see if your car is listed
  • Ask somebody behind the counter at an auto parts store
  • Call a dealership parts desk (not the sales department) and ask
  • Google your car + coolant color (just make sure you verify from a few sources if you go this route)

Q. Can you mix different colors of coolant?

A. The short answer is no, you should consistently run the same color of coolant in your car. Though some coolants are universally mixable and some may be mixable without consequence, there’s no logical reason to mix different colors of coolant.

Q. How do I know if my car needs antifreeze?

A. You can wait until your car starts overheating, or, after the car has cooled, open up the radiator cap and check the reservoir. 

Q. How long does coolant last on the shelf and in your car?

A. How long you can go between changing coolant depends on what type of coolant you are using, your vehicle’s manufacturer recommendations (found in the owner’s manual), how you drive your vehicle, and the climate in which you drive your vehicle, so there’s not one single answer. However, both the maker of the coolant you use and the maker of the vehicle you drive offer guidance and suggestions.

A Valvoline DIY guide, for example, says, “As recently as two decades ago, changing your coolant every two years was the standard recommendation. Then, about a decade ago, that span increased to five years. In many of today’s modern vehicles, a cooling system is designed to allow up to 10 years (or up to 200,000 miles) before adding new coolant. In fact, some vehicles are filled for life.”

In the 2020 Chevrolet Corvette’s owner’s manual, it suggests replacement at 150,000 miles. Honda Type 2 Coolant, however, is rated to last approximately five years or 60,000 miles. Prestone even says its coolant is rated to last 10 years or 300,000 miles, so it all depends. That doesn’t mean you should wait that long to check it, though! As for shelf life, we personally would adhere to the same recommendations from the antifreeze manufacturer, but it’s generally understood that antifreeze should last for years.

Q. What are coolant testers for?

A. Hydrometers or coolant testers can be used to quickly check the concentration of your coolant to make sure your levels are appropriate for your vehicle and climate. 

Q. How much does it cost to fix a blown head gasket?

A. A lot. It likely means your engine is destroyed, which means purchasing a new one and all the parts associated with it that were damaged by the engine melting itself.

See How To Change Antifreeze with this Helpful Video

Some like to read instructions, others like to watch. Check out the job below.

You can buy coolant and antifreeze at almost every auto parts and home improvement store. As well as online stores like Amazon. You have a sea of options to select from. We grabbed a few choices to help narrow down your selection with Car Bible’s Best Antifreeze

Disclosure: Carbibles.com is also a participant in the Amazon Services LLC Associate Programs, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Pages on this site may include affiliate links to Amazon and its affiliate sites on which the owner of this website will make a referral commission.

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