Tips from Used Car Advisor

Car Advisor Tamotsu Todoroki

Hi, this is Tamotsu Todoroki. I am a car advisor of
I write an online column every week to take care of your vehicle. My column is all about something useful and practical for your vehicle. Please have a look once to keep your car in good condition.


Can I Use Water as Engine Coolant? - Vol.195

Car maintenance has evolved significantly over the years. The rapid advancement of technology has redefined what it means to service a car. In place of the springs, latches, and levers that once controlled the mechanisms of our vehicles you can now find sensors, computer chips, and regulators. However, there are still some questions that have remained throughout the years. One of these lingering questions is whether or not water is an adequate substitute for coolant. This is an age-old question that we will now look into.

The Purpose of Coolant
It is important to understand the overall purpose of coolant before determining whether water can serve as coolant by itself. Typically a water-coolant mixture, usually 50/50, is used to satisfy the cooling system. Coolant serves three key purposes when it comes to engine performance: lowering the freezing point, raising the boiling point, and lubricating the water pump.

The interesting thing about coolant is that it also serves as anti-freeze. During the winter months, or in any below freezing climates, a cooling system that is comprised only of water will freeze, and can cause significant damage to your engine. The result of internal freezing can be a cracked engine block, cracked radiator, and seizing of pistons. An engine that receives damage to this extent is either incredibly expensive to fix or cannot be repaired. In this situation the coolant additive works to lower the freezing point of the water and maintain a consistent viscosity.

On the other side of the spectrum is the problem of overheating. You may rationalize the use of water as coolant during the warmer months, but significant damage can occur here as well. The main process that occurs within an internal combustion engine is exactly that, combustion. Countless small explosions power your vehicle, and as a result a large amount of heat is produced. This heat can wreck havoc on an engine that is not properly cared for. Water will serve its purpose momentarily, but as the heat builds the water will begin to evaporate and will cease to be effective. When this occurs, not only will the system overheat, but any lubrication that is present will begin to deteriorate. This combination can cause engine seizure, blown gaskets, and binding of the pistons. Damage to this extent will be close to impossible to repair. However, by adding coolant into the system you will increase the boiling point of the fluid, and prevent overheating.

Furthermore, as coolant makes its way throughout the cooling system it acts as a lubricant for the water pump. This ensures that the system flows seamlessly, and reduces wear and tear.

Further Consideration
It is becoming more common for today's manufacturers to create their own customized coolant formulas. These formulas consist of mixtures and additives that are designed to optimize a specific system. It is important to recognize this and to avoid the use of other coolants, which could cause wear that would not occur otherwise.

It is safe to say that coolant is a necessary addition to the engine's cooling system. However, there are times when it may be necessary to use only water, such as emergency situations. In this case it is important to use distilled water. By using tap water, or water from any other source, you will introduce contaminates to the system. The tiny minerals that the unpurified water contains can build up overtime, and eventually cause damage. Distilled water is free of these contaminates and should be utilized when mixing fluids.

In the end, it is best to play it safe and use the proper mixture of coolant and water to avoid any system failures.