The Engine Coolant: What You Need To Know?

An overheating engine is a problem that can really incapacitate your vehicle. In fact, it is one of the major problems you would like to avoid if you want to keep your engine running for longer mileage. An overheating engine can be caused by plenty of faulty apparatuses in your engine and one of these parts involves the engine coolant.

What is an Engine Coolant?

As its name suggests, the engine coolant is part of your engine that prevents it from overheating. It’s also called antifreeze and it’s a part of your radiator that regulates the temperature by which your engine runs. A coolant is a mixture of equal parts water and ethylene or propylene glycol.

Once you open your hood, you will find the engine coolant reservoir on your radiator. It’s usually in a semi-transparent plastic container found at the side of the engine—depending on the make and model of your vehicle. Older vehicles don’t have a separate reservoir for the coolant, you would need to open the radiator cap to access the coolant.

What does an engine coolant do?

An engine coolant doesn’t keep your engine cool, it serves three purposes: keep your engine from overheating, keep your engine from freezing and to also protect the aluminum parts of your engine.  Your engine will quickly overheat and if that happens frequently, you will end up with an engine failure or a mechanical breakdown.

It’s technically your engine’s built-in air-conditioning. The coolant mixture is pumped throughout the engine by means of a water pump. It goes around the engine and absorbs the heat produced and brings it to the radiator. In turn, the radiator cools the heated mixture and sends it back up the water pump. The radiator always receives an influx of air that serves as the cooling mechanism for the coolant.

An engine coolant mixture should follow equal parts of water and antifreeze. Adding too much coolant would result to a higher boiling point and would decrease freezing point. In other words, your coolant wouldn’t help you much in cold weather. Instead of keeping it warm, it ends up freezing your engine at a lower temperature. And having more water in the mix would result in your engine overheating much faster than it should. A 50/50 mixture is the ideal concoction.

TIP TO REMEMBER: When you find yourself in an emergency and your engine is right about its boiling point, add water to your coolant reservoir. Water can get you out when you’re in a pinch. After that, have your vehicle serviced and flush the coolant out. Water can help in cooling your engine down but don’t get your engine used to it. Water would easily boil up and turn to steam and relying on water alone would also harm your engine. Water will evaporate completely in warmer weather and in extreme cold, it would just as easily freeze up.

What kind of engine coolant should I use?

There are three main types of engine coolants: the traditional green or yellow coolant, orange coolant and the global coolant. Normally, your vehicle comes with a preferred coolant that your engine would most probably work with but with the absence of such guide, choosing the right coolant in rainbow colors can be confusing.

Green engine coolant

Originally, there is the green-colored coolant. It is a glycol-based compound using silicates as its corrosion inhibitor. However, even if the component ‘ethylene glycol’ or EG as the main chemical compound in the coolant is mainly used by most manufacturers a more environment-friendly compound comes into the mix: propylene glycol or PG.

Read Top 10 Best Engine Coolant Reviews

  • Inorganic Acid Technology or IAT

This is the traditional green or yellow colored antifreeze. It is made from either EG or PG and is fortified by silicates or phosphates as its corrosion inhibitor. It is recommended to flush the coolant every three years or every 36,000 miles.

  • Organic Acid Technology or OAT

It is also known as a Long Life Coolant (LLC) or Extended Life Coolant (ELC) is colored orange—in some car coolants like Toyota it is dyed pink. This is usually made with EG with a recommended flushing age of five years or 150,000 miles.  It doesn’t use silicates or phosphates as its corrosion inhibitor. This is not compatible with older vehicles since it only supports the care for aluminum engine components rather than brass or copper radiators.

pink engine coolant

  • Hybrid Organic Acid Technology or HOAT

HOAT is technically a combination of IAT and OAT using nitrites. It uses organic compounds but is fortified by silicates as its corrosion inhibitor. It is often referred to as the global coolant. It’s life span or flushing age is five years or at 150,000 miles.

What color of coolant is matching?

Manufacturers often build cars with specified chemical components that are preferred by the model’s engine. Different car brands prefer differently colored coolants like Toyota, Volkswagen or Audi models use the pink colored OAT coolant but Honda uses a dark green OAT coolant.

Make sure you know what type and color coolant your vehicle originally had before replacing the coolant. Experimenting on what type of coolant works best for your vehicle might reduce the life of your coolant and may reversely affect your radiator. Different active chemicals found in different vehicles may damage the interior of your radiator making it prone to corrosion.

How to check engine coolant level?

Once you pop your hood, you can easily spot your coolant reservoir. It comes in a semi-transparent container with a level line that says ‘Full’. Make sure it doesn’t go under the line, if it does just add more coolant. Some vehicles—old ones especially—have coolants found inside the radiator. You would need to open the radiator cap and check if the level of your coolant is lower than the specified amount it should have.

What does engine coolant low mean?

Engine Coolant low

When your ‘engine coolant low’ light pops up it simply means you don’t have enough coolant in your reservoir. It means that there is an insufficient supply of coolant that regulates your engine’s temperature thus affecting your engine’s performance because it is not cooling efficiently resulting in extensive damage to your engine.

What are the low coolant symptoms?

  • Decreased performance

Coolants directly affect the performance of an engine. An engine that heats up really fast means that your engine’s cooling system is faulty and one of these are caused by a low coolant level. Your vehicle will have a hard time during summer or winter when your coolant level is low. Engine fluids will freeze in winter if you don’t have enough antifreeze in your car. This will incapacitate your vehicle since your engine will not be able to function properly. Your engine will also overheat extremely fast because there is not enough coolant to absorb the heat from the engine.

  • Sweet Unidentified Odor

A colorful coolant comes with a sweet odor. Once you smell a sweet odor that doesn’t seem familiar, check under your hood and see if your coolant level is getting low. This may be due to a leak in your cooling system. Any leak will easily affect your engine’s performance.

  • Greasy Window

Oftentimes you spot grease on your window so it doesn’t seem so unnatural. However, if you wipe it off and the film returns quickly it means that your coolant may be leaking. The greasy film on your windows may be due to the exhaust or evaporation of your hot coolant. Chemical vapors come about when your hot coolant is exposed. Double check on greasiness inside your vehicle, it may not just be because of your coolant but other fluids needed by your vehicle.

  • Colorful Leak

Colorful leak definitely means that your coolant is leaking off. The only colorful fluid in your vehicle is your coolant and spotting a colorful leak is definitely the reason why your low engine coolant light is lit on.

  • Discoloration

Your Low engine coolant light may also be lit on not due to insufficient coolant but because of the fact that there is not enough coolant running through your cooling system. Your vehicle runs well with a decent amount of coolant regulating the heat in your engine. Once you notice that your coolant’s color is different than before then you should definitely have it replaced. A discolored coolant may mean that there is present corrosion, rusting or unwanted chemical reaction involving your coolant. This may damage your radiator and your engine.

  • Too Cold or Too Hot Passenger Compartment

Whenever you drive your vehicle, it often feels warm right by your feet and legs. Once you notice that it is unusually hot or cold, you should check your cooling system. The coolant’s function is to maintain a heat signature in your engine so that it will perform well but if your seating temperature is unusual it may be due to the insufficient amount of coolant absorbing the heat and distributing the cool temperature throughout your engine.

What will happen if I continue running when the engine coolant is low?

You can already predict what happens if you ignore your lit low engine coolant light. It directly affects almost all functions of your engine because it is the only thing that keeps your engine performing properly. Driving your vehicle with low coolant levels would result in the following:

  • Overheating engine. Primarily, your engine will definitely overheat due to different reasons. If your coolant is low:
    • Your engine parts will warp. Heat can misshape any metal parts in your engine. Your engine is practically a huge block of metal that can warp due to increasing temperature. Your engine will lose its integrity and may even result in a complete engine change is a lot of your engine parts warped due to high heat.
    • Your piston will expand. Due to the heat, your piston will expand. If this happens your piston will rub violently against its cylinder casing causing it to either stop or damage the piston and the cylinder casing. This going to be a very expensive trip to your mechanic.
    • Your cooling system will fail. Low coolant levels will cause higher pressure in your coolant hoses. Due to the lack of coolant being pumped into the hoses, your radiator will compensate the loss by pumping under greater pressure to deliver the coolant throughout your engine. This will cause your hoses to burst thus spurting coolant throughout your engine and this can be damaging.
  • Expense. Damage directly or indirectly caused by a low coolant level will result to your pocket pumping quite an amount of money. It would be better to buy a secondhand vehicle rather than fix an engine failure caused by the low coolant.
  • Dry Water Pump. The water pump is dependent on a sufficient amount of coolant mixture since it needs to run with proper lubrication and resistance. If there is not enough coolant in your reservoir, your water pump with eventually give out.
  • Partial or complete loss of internal heating functionality. Internal heating dependent on your coolant will not function since heat is inefficiently absorbed by the coolant will not deliver well and will probably cause you to practically suffer from the cold due to this.

What should you do about low engine coolant?

You may either add more coolant to your reservoir or simply flush it out and replace the mixture to ensure better efficiency.

Overheating Engine

  1. Let your engine cool down.
  2. Remove your radiator pressure cap to drain the coolant in the hoses by wrenching out your engine block drain plugs.
  3. Reinstall the drain pugs.
  4. Fill-in your reservoir until it hits the required amount of coolant needed by your vehicle.
  5. Turn on your vehicle and let it stand idle. Check if the coolant is circulating before replacing the radiator cap.

To keep your engine running, keep your coolant well and maintained to avoid a much more costly problem.


The Engine Coolant: What You Need To Know?
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