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How Much Antifreeze Should Be In Your Car?


Engine coolant isn’t something that is readily on most driver’s minds. Most don’t know how it works or that antifreeze is a component within engine coolant. However, most do know that if you don’t have enough engine coolant in your vehicle you are in for a big problem. Engine overheating can lead to some serious repairs, but you can avoid this issue by thoroughly vetting the integrity and volume of the coolant in your car.

So how much engine coolant, or antifreeze does your car hold and how full should it be? It will vary from vehicle to vehicle, but you want to keep you coolant levels topped off to the max fill line at all times. Most cars have 5 liter engine coolant tanks. You can buy engine coolant in bulk or by the 1 liter however, if you are topping up a reservoir that isn’t empty, use the same brand of antifreeze as last time. Different coolants can mix to produce dangerous chemicals that can cause engine damage. Engine coolant should be drained from the radiator and replaced entirely every 5 years or 100,000 miles on average.

Engine Coolant Volume

Engine coolant is an important fluid to keep topped off and clean in your vehicle if you want to keep the engine running in top shape.

An average cooling system in a vehicle will hold 5 liters of engine coolant, which is a mixture of antifreeze and water. You can buy engine coolant in bulk or by the 1 liter however, if you are topping up a reservoir that isn’t empty, use the same brand of antifreeze as last time. Different coolants can mix to produce dangerous chemicals that can cause engine damage.

If that’s all you came for we wish you well! If you’re interested in learning more about antifreeze, engine coolant, the differences between them and how to properly care for your coolant system, read on below. 

 But before we get into that, it is instructive to understand why your vehicle has coolant in the first place and how to identify the reservoir that the fluid resides.

Finding The Engine Coolant Reservoir

You can easily identify the engine coolant reservoir by looking for the brightly colored lid. In most vehicles it is yellow and has some form of warning o the car warning you that this compartment is pressurized when the engine is hot. It is important to only open it when the car is completely cool. You should be able to check your fluid level just by looking at the compartment as it is a translucent plastic and inside you’ll find a brightly colored liquid.

For specifics on where your car’s coolant reservoir is, we encourage you to check your owner’s manual which should have some form of visual representation of the location for your make and model. You can also find this information online by utilizing a simple Google search.

How to Check your Engine Coolant Level

Engine coolant isn’t something that needs to be checked weekly unless your car is leaking fluid, which is serious not only for your car and for the environment and should be addressed promptly. If your vehicle is not leaking fluid, checking your coolant levels every 2 to 3 months should be sufficient. If you top it off at this time you should likely have no problems.

The process of checking your coolant is very simple and anyone can do this on their vehicle. Once you’ve popped the hood open and have located the reservoir you can check the fluid level without even opening it. The clear plastic will hold a colored fluid inside which may be yellow, pink or orange. The container has a maximum and a minimum fill line marked on it. The coolant should be topped off ideally, however you won’t have any issues generally unless the fluid drops below the minimum fill line.

Back in the day, antifreeze/coolant was a single type. Now many auto manufacturers require specialized coolants to maintain the vehicle’s cooling system and protect the engine from damage. Here are the various types of coolant your car may use.

The 3 Types Of Engine Coolant

There are three common varieties of engine coolant: they are inorganic additive technology, organic acid technology and finally hybrid organic acid technology. 


This solution is outdated and is less superior than its competitors nowadays. As there are now more effective options on the engine coolant market you typically only see inorganic additive technology in older vehicles. 

If your car uses this type of engine coolant it is important that you stay on top of flushing your system and replacing your coolant. 

Inorganic additive technology coolant must be changed every 24,000 miles or two years, whichever comes first. This is far more frequent than newer coolants that are on the market. 


The next coolant we are going to discuss is much more with the times and requires far less maintenance and upkeep. It is increasingly popular in vehicles newer than the year 2000. 

Organic acid technology coolant, which is widely used by General Motors, only needs to be changed every five years or 150,000 miles! That is a remarkably long length of time that you can go without replacing your coolant. This saves these car owners time and money involved with maintenance procedures. 

This variety of OAT coolant is traditionally orange or red in color. 

It is derived using fully neutralized organic acids and azoles and these are the components that make the fluid anti corrosive. This is also where the substance received its name. 


Finally we have Hybrid Organic Acid Technology which is a slight variation of Organic Acid Technology. Both of these coolants have essentially comparable replacement cycles 

How To Top Off Your Car’s Coolant Levels

Most car owner’s are capable of topping off the coolant in their car. It is a simple process that just about anyone can do. The most important thing to remember is to NEVER touch the coolant reservoir when the car is hot. The compartment becomes pressurized and will shoot out molten hot liquid. Once the car cools down it is completely safe to open the cap and top off the fluid. Here are the steps you should take:

  • Start with the right coolant —  As we discussed in the section right above this one, there are different varieties of engine coolant and your car will take one in particular. In addition to making sure your car is getting the right coolant, some coolant types should not be mixed with others and can cause severe chemical reactions if mixed. Check your owner’s manual to verify the type of coolant your car takes.
  • Let the car cool off completely — You risk severe burns from hot engine coolant if you do not let the car cool of completely.
  • Follow the instructions for diluting concentrated coolants — Some coolants are sold in concentrated form and will need to be diluted before being added to the coolant reservoir. It’s important to check the coolant label found on the container for instructions on this. In addition to concentrated coolants, some engine coolant is sold in a ready to use format and requires no diluting.
  • Remove the cap and funnel in the coolant — After allowing the engine to cool completely, remove the cap and add in the new coolant to the reservoir. Do not overfill the tank as this system becomes pressurized when the car is hot and needs the extra room for expansion.
  • Replace the cap — When you have finished filling the tank simply replace the cap. Be sure it is put on tightly and the reservoir is sealed.

A Brief Introduction On How The Cooling System Works (If You Care)

Combustion engines found in cars use energy from controlled engine explosions to propel them forward. However, the typical combustion engine produces twice as much energy in heat as it does in energy used towards forward motion. 

If this heat is not displaced of properly it can quickly destroy an engine. The job of your car’s cooling system is to release that excess heat in a way that is safe for you and your vehicle. Most modern vehicles use what is called a liquid cooling system. In this design, a water pump circulates coolant through your engine using plumbing and hoses to cool off the hot parts of your car’s engine. 

The now warmer (really freaking hot) fluid is then pumped into the radiator which works to cool the fluid back down using the ventilation and air flow from the front of your vehicle. The fluid is then recirculated into the hot engine to cool it down further. The process repeats continuously as the vehicle drives.  

Your engine has a thermostat that measures the temperature of the coolant in the car. When your car is cold the thermostat will bypass the radiator and send the fluid directly back into the engine until the engine is hot and is readily heating the coolant. 

Why Cars Have Issues With Overheating

Typically when your engine overheats it is most likely caused by faulty or old engine coolant. The controlled gasoline explosions within the average car’s combustion engines is pushing 500 degrees and this is far too hot for most of the engine parts. 

If there isn’t enough coolant or the coolant is old and not functioning properly it may get hot enough to boil. Any boiling liquid is incapable of taking on any more heat until it becomes a vapor.

If the engine coolant starts to boil it is no longer effective at cooling down those metal engine parts that are being exposed to those scalding hot temps. When that metal heats up past a certain temperature a number of things can happen and none of them are a positive for your car. 

Typical repairs after an engine overheats include warped cylinders, cracked head gaskets and busted water pumps. The repairs average about $700 to fix just one of these issues. That is why it is imperative to ensure your engine coolant is not old and deteriorating. 

What Is Engine Coolant?

Engine coolant is the liquid that surges through your engine removing heat and keeps your car from overheating. 

This is no easy feat considering the controlled engine explosions that move your car forward get up to around 495 degrees F. These can lead overall engine temperatures up into the 200-220 degree Fahrenheit range when you are driving continuously. 

To do its job properly, the fluid that gets pumped through your engine and prevents catastrophic heat damage MUST have a very low freezing point and a very very high boiling point. The reasoning here is that if the fluid freezes, it could crack the cooling system and also won’t be effective at cooling the engine until it melts, and if it boils it can’t remove heat at all.

Water alone does not meet these requirements. 

To accomplish these goals, we use a solution typically referred to as engine coolant. It is common for an additive called antifreeze to be included as a large part of this solution. 

Though antifreeze in its pure state actually freezes and boils more quickly than water, when it is mixed at a proper proportion with water, it actually lowers the freezing point of the mixture and increases the boiling point. It also prevents corrosion in your engine. Coolant is generally a 1:1 ratio of antifreeze to water. 

Why We Use Antifreeze

Water freezes at 32 degrees and boils at 212 degrees. Because engine temperatures can sometimes drop below or exceed these ranges we must use additives to prevent the freezing and boiling of the fluids within the lines of your car’s radiator. 

If that liquid were to freeze it would break your engine. If the fluid reaches a boiling point it will no longer be able to serve as a heat transfer between the hot metal in the engine block and the car will overheat. 

Engine overheating causes warping of several important components of the engine like the aluminum cylinders, engine head gasket and water pump. 

When water is mixed with antifreeze (which is made of a chemical called ethylene glycol), the freezing point is bumped down to -35 degrees and the boiling point raised to 223 degrees Fahrenheit. 

This makes ethylene glycol the perfect additive to our cooling system!

The 3 Jobs Of Antifreeze

Engine coolant serves 3 important purposes:

  1. Removing heat from the engine block by raising the boiling point of the fluid above the normal temperatures seen in a car engine block.
  2. Lowering the freezing point of the liquid in the coolant reservoir so that the liquid doesn’t freeze at 32 degrees F and break the engine.
  3. Antifreeze serves as a corrosion inhibitor to the engine, radiator and heater core.

What Is The Difference Between Engine Coolant And Antifreeze?

Though people use the terms interchangeably, coolant and antifreeze are actually not the same thing. You can’t put pure antifreeze into your car and have happy results. Engine coolant refers to the liquid mixed solution that surges through the engine block in your car keeping it from overheating. It is important to note that it is a solution, meaning it is made up of a mix of several substances. 

Engine coolant is a pre-mixed solution which will contain antifreeze. Alternatively, you can buy antifreeze as a concentrate and mix it with softened water and make your own, if you know what you are doing.

Antifreeze is a chemical, ethylene glycol, which is found in most premixed engine coolants that are ready to be added to your vehicle. It is also sold separately as a pure substance ready to be mixed with SOFTENED WATER and then funneled into your car’s cooling system (after you have read the manufacturer’s instructions and safety warnings). 

To reiterate, your options here are to purchase a premixed engine coolant that is ready to be added to your empty, clean, engine coolant compartment in your car. Or you can purchase anti-freeze and mix a 1:1 ratio with softened water. Always read the mixing instructions to verify safety procedures and mixing ratios which may vary from brand to brand.  

I have included some information further along in this article to help you clean out your engine coolant system of all old, used and dirty coolant and to help you dispose of it properly. 

If you are topping up a reservoir that isn’t empty, use the same antifreeze as last time. Different coolants can mix to produce dangerous chemicals that can cause engine damage.

REMEMBER antifreeze is toxic and has to be disposed of properly! Please be sure to keep your used and replacement coolant away from animals it tastes sweet to them and they will drink it. 

When Should you Change your Engine Coolant?

Engine coolant, like many other parts and fluids within a vehicle, is becoming increasingly advanced as we make strides forward in the automotive industry. As engine coolant has progressed, it needs less maintenance.

One of the maintenance items that is now less frequently required is the flush and fill procedure where the coolant reservoir is emptied, cleaned and filled with new engine coolant. Your car will have a recommended maintenance schedule that you can find online or in your owner’s manual. For information on how frequently the coolant needs to be replaced for your car seek out information there. On average, you should flush your radiator and refill it with fresh coolant once every five years or every 100,000 miles .

Procedure For Safe Flush And Fill Of Radiator

Most of my readers are interested in engine coolant because they are actively undertaking the replacement of their engine coolant themselves. This is awesome and will save you guys some money, however you need to make sure you are replacing the fluid properly and especially that you dispose of your old coolant in a responsible fashion. 

I found this youtube video exceptionally helpful when it came to flushing my cooling system replacing my own engine coolant. It will talk about:

  1. SAFETY. Cooling systems are pressurized and you need to ensure you are using your car when the engine is cool. We don’t want you to get scalded by super hot engine coolant, okay? Please pay attention to these warnings he gives you. 
  2. What preparations you need to make before flushing your engine’s cooling system. Generally it is suggested that you use a chemical coolant flush several days before actually flushing your engine. 
  3. The section in which you can look within your owners manual for information regarding what engine coolant you should personally use for your car.
  4. How to disconnect and reconnect the hoses in your cars cooling system so that you can attach a hose and flush the system.
  5. How to ensure the engine cooling system has been drained entirely.
  6. What to drain your old cooling fluid into.
  7. Safe handling and disposal of used engine coolant.
  8. He even shows you the change in color with each of his five or so engine flushes!
  9. Finally, the video shows him replacing the engine coolant with new coolant. 

Safe Disposal Of Old Engine Coolant

Be careful with your used engine fluid during the removal process as it is toxic and should not simply be dumped out with the trash or down a drain. 

It needs to be disposed of properly. Be sure to transfer the liquid into something watertight. It needs to be in a container that will be feasible to put in your car to take in for recycling. 

Used engine coolant can be properly disposed of pretty easily. Most mechanics will take it off your hands for free (they make money when they sell it off to the disposal companies).

You can also recycle the fluid at your local disposal center or hire a private waste disposal company to come pick it up from you. 

I reiterate here, engine coolant is toxic. We do not want it in our water systems, in our pets or in our children. That would be bad. Be responsible. 

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