Coolant is one of the fundamental liquids for the engine to function properly. Its main task is that the mechanics always have the ideal temperature: a combustion engine tends to heat up and needs to be cooled periodically. At the same time it has an antifreeze function, so that the low winter temperatures do not affect it as much.
As you can see, it is an essential element for a car with a combustion engine… and also in electric cars. Although the latter do not require lubricating oil for mechanics, they do use coolant to maintain optimum levels of engine and battery temperature.
We are going to analyze all the key aspects of the coolant liquid (also called antifreeze, although this is one of its properties). We will also see what you should check to avoid much more serious, difficult and expensive mechanical problems to solve.
What is coolant used for?
The coolant liquid prevents excessive heating of the combustion engine, so that it works at the correct temperature and does not lower performance. In the event that the mechanics overheat, there is a risk of self-detonation of the fuel, failures in the head gasket or even seizing the engine, possibly one of the most serious failures.
Engine cooling was done by air in many vehicles, but with the evolution of engines equipped with more complex technologies, the need to lower temperatures increased and today they are almost non-existent in cars with this system. The usual thing is to bet on liquid cooling to better absorb excess heat from the engine, caused in the cylinder’s combustion chamber.
These are special liquids, with properties beyond cooling or preventing freezing, since they help prevent metal corrosion, even aluminum or light metals, by preventing calcareous formations that could occur with liquids such as water.
What coolant to use
When choosing the best coolant, there is no doubt: always the one recommended by the manufacturer for your vehicle. So check the car’s maintenance book to know its characteristics. The colors can determine them… but be careful, since each manufacturer follows a different color code.
Each color of refrigerant (usually green, orange, yellow, blue or pink), represents its level of efficiency. Freezing temperature, for example, is related to the amount of ethylene glycol (antifreeze) that incorporates. That way, if you have 10% ethylene glycol you can use between -4ºC and 102ºC, 25% from -12.5ºC to 103ºC. The maximum level of ethylene glycol is 50%, so they can be used between -37ºC and 108ºC.
Ethylene glycol stands out because, in its pure state, its boiling point is about 197 ºC, which is why, since the late 1930s, it has become the most common car antifreeze. It overtook ethanol, which tended to evaporate.
The only reason to choose so bright colors is to be able to quickly locate and identify a leak. They are not common, but the problems that a lack of this liquid can cause the car are so serious that it is better to detect it as soon as possible. Remember that leaks (of any liquid) can cause an unfavorable ITV.
In any case, there are a series of guidelines that a good coolant must meet:
- low freezing temperature: to increase the volume of liquid when cold (could break the refrigeration circuit). It is expressed on the label, in degrees Celsius.
- high boiling point: greater than that of the engine in operation, so that when it fulfills its function it retains properties and does not evaporate.
- Anticorrosive and antifouling properties: which prevents solid deposits from forming and calcium build-up. The label indicates the pH (corrosion capacity of the liquid on metals), amount of alkaline inhibitors and maximum amount of residues.
- low viscosity: so that it can flow easily. It is expressed in gr/cm2.
- anti cavitation: that it forms few foams (they can clog the circuit). The label indicates the time it takes for the foam to disappear, less than 5 seconds and having a maximum volume of 50 ml.
- storage stability: the maximum time that it can be (minimum one year in the original container between –18ºC and +50ºC).
Types of coolant
There are several types of refrigerant, called G11, G12, G12+, G12++ and G13. There are no better or worse, as we indicated, each one is indicated for a specific vehicle and the climatic conditions in which it is going to move (yes, it is possible that the same car in Almería and Moscow have different coolants). We can divide refrigerants into several types:
- Organic coolant: Formed by ethylene glycol (the antifreeze component) and distilled water, in charge of guaranteeing protection against corrosion. It stands out for being stable for long periods and being biodegradable (less harmful to the environment). They generate fewer solid deposits inside the refrigeration circuit, have low electrical conductivity, and have a higher boiling point. As a general rule it is red or pink.
- Inorganic coolant liquid: Like the previous one, it is made up of ethylene glycol, the most common antifreeze agent, but it is another product, such as silicates, that prevents corrosion. They last less and can be distinguished by their blue or green colors.
- Hybrid coolant: They combine both, by having ethylene glycol, glycerin and antifoam, anti-limescale additives and a neutralizing reserve that will protect the refrigeration circuit. They can incorporate silicates to protect aluminum parts.
- Anti-corrosion coolant: Incorporates anticorrosive additives to prevent corrosion from occurring in the elements of the refrigeration system. it achieves a higher boiling point, avoiding overheating, freezing in winter and the formation of metal oxides.
- Antifreeze coolant: It is used for extremely cold climates, with freezing temperatures well below zero degrees.
Can I mix coolants?
Quick answer: No. The type of coolant used by the car is specified in the vehicle’s maintenance book and in the expansion tank. Always use one with the same characteristics.
In an emergency, pay particular attention to these factors:
- Never mix coolants of different origin. An organic with an inorganic or hybrid can end up forming a solid paste that clogs the circuit. Even just pouring a little to complete the level.
- Never mix coolant liquids different color. In a pinch you can complete with one of the same color (their basic properties will be similar), although it is not ideal.
- refrigerants G11, G12, G12+ they can only be combined with another of the same characteristics. For their part, the G12++ and the G13 can be combined.
Where does the coolant go?
The refrigerant liquid moves through a circuit. The most visible part is the filling cup, which is usually made of transparent plastic, with a black or blue cap. Note, these are general details. If you have any doubts, refer to your vehicle manual or ask an expert.
It is a hermetic circuit and it is unusual (not impossible) for a leak to occur. But just in case, it is best to monitor your condition from time to time.
Check coolant level
It is a task whose greatest complexity is to open the hood of the car. Once you’ve done that, follow these steps:
- Locate the filling glass (that deposit we talked about before).
- Since it is usually transparent, you will see through it the liquid of a striking color. There are two brands, with max and min level. It has to be between the two.
- Be careful, the car must be in a flat surface when doing this check. Check with the cold engine to be more exact. And it is that with the engine still hot it tends to increase the level of the circuit and exceed the maximum mark.
Top up coolant
If the coolant level is below the minimum, it may be a sign of a leak. The best thing in this case is to fill the deposit and check after a while. If it persists, go to a workshop to locate why it loses.
It is an operation that anyone can perform, taking care not to confuse the type of liquid to be poured. Follow these steps:
- Locate the filler cup cap
- With the engine cold, open it. This is important, because with the engine still hot you can burn yourself.
- It is a sealed closed circuit. This means that it may take a while to open it, it is normal. Go turning gradually so that the decompression is gradual.
- Fill until the level is between the minimum and maximum marks. If you have a bad pulse, use a funnel.
Can I refill with water or distilled water?
If your coolant level is low, you may be tempted to top it up with water:
- Tap water: Absolutely, don’t do it. So much so that we dedicate an article expressly to this topic. As you know, it freezes at 0ºC (it could break hoses, pump or connections) and it boils at 100ºC, it would not fulfill the antifreeze or refrigerant function. Also, water corrodes metal
- Distilled water: It is the lesser evil and, in fact, a compound of it. But be careful, because lowering the properties of the refrigerant.
When to change the coolant?
Changing the coolant depends on each manufacturer. The usual thing is that it has to be changed every two years, or every 40,000 kilometers. It is not that the liquid will lose its antifreeze capacity, but there may be a reduction in other properties, such as anticorrosive.
If a coolant spends too much time in the car, it can end up damaging components of the cooling system such as the radiator, thermostat, pump… Changing the coolant, although it implies completely emptying the circuit to eliminate the remains of the old liquid, it is not an expensive maintenance operation and avoid future breakdowns that can be really serious and expensive.