Motoring: Water vs coolant- which is better for your car?

It is important to note that the engine starts to heat immediately after the car is ignited. The water or coolant is injected into the engine through the radiator.

With the pistons moving, the engine generates intense heat that needs to be cooled off to prevent overheating and subsequent damage including knocking of the engine.

This is where the water and or coolant come into play. In the Western world, the coolant most used is antifreeze due to the extreme temperatures that can drop to the extremes of -4 Celsius.

So, Water or coolant?

Charles Okoth, a mechanic in Nairobi recommends the usage of pure coolant in running engines, stating that although water works as well, it is a short-term solution.

"In Kenya, most motorists use plain tap water because it is readily available and sounds like a cost-effective solution. But, in the long run, the usage comes with significant drawbacks majorly being corrosion," Okoth argued.

Scientifically, tap water has a freezing point of 0°C and a boiling point of 100°C, offering no protection against extreme temperatures.

Disadvantages of using water

While the usage of water in the radiator is common in tropical countries, the opposite is true in Europe and other countries that experience winter (extreme climates).

Water is the only known non-metallic substance that expands when it freezes; its density decreases and it expands approximately nine per cent by volume.

"During winter, frozen water can expand and in the process lead to cracked engine blocks or burst hoses. Remember both the radiator and the engine don't have room for expansion," the mechanic opines.

The same applies to heating since boiling water can result in overheating and even blowing of the head gasket.

Corrosion peril

Corrosion is a chemical reaction between water and metals that breaks down the metal's surface.

It is also key to note that compared to coolant, water doesn't contain additives that are meant to prevent wear and tear. This exposes the engine and the cooling system in general.

Why coolant is most preferred

With the two chemicals mixed (ethylene glycol or propylene glycol), the coolant is armed with capabilities of preventing freezing during winter and also boiling in extreme temperatures.

Most coolants can function effectively in temperatures ranging from -37°C to 135°C, depending on the mixture ratio.

The chemicals infused in a coolant contain rust inhibitors that prevent the radiator and engine from being attacked by rust.

"It is easy to maintain an engine's lifespan if you use coolant because you don't have to pop up your hood and top up water all the time.”

Coolant will give you better service and can serve up to 40,000km, before changing when it comes to your car's cooling system," Dickson Musungu, another mechanic weighs in.
Joshua Otieno, a BMW specialist, warns against using substandard coolants.

"Some of the cars that I work on with cooling problems, have had their pipes damaged by the chemicals. It’s always good to invest in quality brands and not those sold in dodgy stores. It will cost you," says Otieno.

Car experts also concur that modern coolants are formulated to be compatible with a variety of metals including aluminum which is vulnerable to corrosion.

What of coolant and water mix?

Interestingly, all car manufacturers agree that coolant is supposed to be mixed with water. But not just normal tap water, distilled water.

But why distilled water? Because it lacks minerals that contribute to scaling and deposits in the engine and radiator.

Automotive experts recommend a 50/50 mix (of water and coolant) for optimal performance. This recommendation is based on the principle that water has the best heat transfer capabilities while coolant, on the other hand offers the best protective properties (anti-rust).

Water is not suitable for prolonged use in modern vehicles and has zero capabilities of regulating temperature and instead, aids corrosion. With time, you might be forced to change the radiator and corroded water hoses.

NOTE: The market is flooded with counterfeit coolants that could cost you in the long run. Always choose trusted brands for your vehicle.