Is Car Engine Coolant Just Water?


Sep 30th, 2020

Is Car Engine Coolant Just Water?

A functioning engine comprises of several moving parts, some of which are tight and don't allow good airflow. As these parts move, they cause friction and emit heat which if not checked would damage or melt some engine parts in a matter of seconds. That's why your car should never lack an engine coolant. So what is a car engine coolant? Is it water? The simple answer is No. But can you use water as a coolant? Read on to find out! 

What is car engine coolant, and what does it do?

Coolant, or antifreeze, is a special liquid with additives that help maintain the engine temperature at the optimum level. Normal water boils at 100°C and freezes at temperatures below 0°C. Coolant, on the other hand, will not evaporate at 100°C and will remain a liquid at 0°C, making it the ideal fluid to cool your engine at any weather.

How does an engine coolant work?

The coolant flows to the engine block through pipes and passages, picking up heat as it goes. After circulating and absorbing heat, the hot coolant then flows to the radiator found at the front of the car. The radiator, also called heat exchanger, cools the liquid and sends it back to the engine to pick up more heat. The cooling system repeats this cycle to prevent overheating

Coolants, aka radiator fluid, need to be replaced every 2-3 years but must be checked at least twice a year if the level is within the guide marks. If not, then you need to top it off. Always refer to your manual for the correct mixture. 

How do I know the right coolant for my car?

When it's time to replace your coolant, you need to decide on the best product for your car. The first thing you do is to check your owner's manual for the manufacturer-recommended coolant.

Also, do not choose a coolant based on price. Opting for a cheaper "universal" coolant can be a costly mistake. Your car may require a specific coolant formula. Buying a cheap one because it ‘serves the purpose’ will save you some dollars, but cost you thousands in the long run. 

What are the components of coolants?

Just like any product, the effectiveness of coolants is determined by its ingredients. Most high-performing engine coolants contain the following:

  • Ethylene glycol - This ingredient has been used in coolants for over 70 years. It's what keeps the coolant flowing in extreme temperatures (above 100°C and less than 0°C). It keeps the coolant as it is, liquid. 
  • Propylene glycol - Some coolants contain this in place of ethylene glycol. It is more viscous (a minus point since it makes it less efficient in heat transfer than ethylene glycol) and less toxic if ingested.
  • Water - Most coolants have 50% water. When using antifreeze, you can add water to it at a 50/50 ratio because it does not contain water.

Coolants come in various colours but are typically green. Some more advanced coolants come in red, yellow, blue, orange, and other colours.

Pro tip: If the car is still under warranty, use the same colour of coolant originally provided.

Can you use water instead of coolant?

Water is one component of coolants. Before, manufacturers used to recommend coolants with 50% coolant and 50% water, but their stance has since changed to 70% coolant or at times 40% depending on the manufacturer. 

Is it safe to use tap water? NO! You can use it in an emergency (in extreme situations where you need to move as fast as possible), but it can be detrimental in the long run. Tap water contains several minerals which can be harmful to the engine. Mineral deposits in the radiator, water pump and plumbing may cause these car parts to fail or be less effective, resulting in overheating. Continuous use results in the building up of calcium and magnesium in the cooling system (hard water scales).

Conclusion: Use the correct coolant, not just water

Smart people always weigh the implications of their actions in the long term. Replacing your car engine coolant with water will result in serious issues, and you may have to replace expensive components of the cooling system or, worse, the engine. Please follow what your manual says and buy only the recommended coolant. 

PRO TIP: Always have at least 5 litres of coolant in your car at all times, just to be sure. 

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By Eric Anyega