Understanding the functions and precautions of antifreeze

The full name of antifreeze should be called antifreeze coolant, which means coolant with antifreeze function. Antifreeze can prevent the coolant from freezing and cracking the radiator, and freezing the engine cylinder block or cap during cold winter parking.

Many people think antifreeze is only used in winter, but antifreeze should be used all year round.

Chemical composition

More than 95% of water-based antifreeze at home and abroad use ethylene glycol. Compared with tap water, the most significant feature of ethylene glycol is antifreeze, while water cannot prevent freezing. Secondly, ethylene glycol has a high boiling point, low volatility, moderate viscosity, little change with temperature, and good thermal stability. Therefore, glycol-type antifreeze is an ideal coolant.

Types of antifreeze

There are many kinds of antifreeze, such as calcium chloride (CaCl2) in inorganic substances, methanol (CH3OH), ethanol (C2H5OH, commonly known as alcohol), ethylene glycol (C2H4(OH)2, commonly known as sweet alcohol), propanetriol (C3H5(OH)3, commonly known as glycerin), lubricating oil and sugar and honey. Which are common in our daily life, can be used as the mother liquor of antifreeze. After adding an appropriate amount of pure soft water (water without or with a small amount of calcium and magnesium ions, such as distilled water, unpolluted rainwater, snow water, etc., whose water quality has a total hardness component concentration between 0-30ppm), it can become antifreeze in the general sense.

Since methanolethanol is more volatile, it is not suitable for use in northern vehicles.

Functions of antifreeze

In addition to antifreeze, antifreeze also has the following advantages.

Anti-corrosion function: The engine and its cooling system are made of metals, including copper, iron, aluminum, steel, and solder. These metals are in contact with water at high temperatures and will be corroded over time and will rust. The antifreeze will not only not cause corrosion to the engine cooling system but also has the function of corrosion prevention and rust removal.

General use: Automobile, train internal combustion locomotive, tractor, ship, engine, water tank and various mechanical equipment, diesel engine, gasoline engine, and other cooling systems as coolant. It has a variety of functions such as anti-freezing, anti-boiling, anti-corrosion, and waterproof scale. The boiling point of water is 100℃, and the boiling point of high-quality antifreeze coolant is usually 110℃ above zero so that when used in summer, antifreeze coolant is more difficult to boil than water. The biggest headache for drivers using water as a coolant is the problem of limescale, which adheres to the metal surface of the water tank and water jacket, making the cooling effect worse and worse, and it is difficult to remove. High-quality antifreeze is manufactured using distilled water and with anti-scaling additives, which not only does not produce scale but also has a descaling function.

Of course, if your water tank scale is very thick, it is best to use the tank cleaner to thoroughly clean before adding antifreeze. Like water, it has the advantages of large specific heat, high latent heat of evaporation, and easy replenishment. When the ambient temperature is below zero, the water in the cooling system will be transformed into ice. The cooling system components will be at risk of expansion and cracking when the antifreeze can be used to ensure that the engine normally works at low temperatures.

With the improvement of engine structure and material technology, modern automobile engines compared with old engines, a significant feature is the high operating temperature of modern engines, the normal upper limit of the working temperature is generally more than 100 ℃. Domestic cars, for example, the normal working temperature of the engine is Shanghai Santana 90 ℃ ~ 105 ℃, FAW Jetta 85 ℃ ~ 115 ℃, Fu Kang 90 ℃ ~ 118 ℃. If all water injection, when the engine temperature reaches 100 ℃ will be boiling water “boiling,” the water is corrosive and will produce scale affect the cooling effect. So we need to use a special cooling medium – antifreeze.

Some people think that antifreeze is specially used for vehicles in cold areas, which is a misunderstanding. The main component of antifreeze on the market is ethylene glycol, which has a high boiling point and a low freezing point. The antifreeze also contains additives to prevent the oxidation of glycol (which will form more corrosive by-products), prevent corrosion, prevent the production of foam, etc.

Protective effect: First, it plays an anti-corrosion protective role for the components of the cooling system. Second, to prevent limescale, to avoid reducing the radiator’s cooling effect. Third, to ensure that the engine can work within the normal temperature range.

Therefore, the engine antifreeze must have the characteristics of antifreeze, anti-pot, anti-corrosion, water scale, no foam, and is not affected by the season and the region. Among them, the freezing point and boiling point are the basic indicators of antifreeze.

The use of antifreeze must pay attention to the quality. If the quality of antifreeze is poor or even counterfeit, it will not be able to play the role of antifreeze. Coolant is prepared by mixing antifreeze with water in a certain ratio. Auto manufacturers usually specify in the user manual for different low-temperature antifreeze grade antifreeze mixture ratios but also specify the type of antifreeze, can not be mixed. In general, when the ratio of antifreeze to water is 40:60, the boiling point of the coolant is 106℃, and the freezing point is -26℃ when 50:50, the boiling point of the coolant is 108℃, and the freezing point is -38℃.

Therefore, the general requirement is to prepare coolant in accordance with the minimum local temperature of about five ℃. Antifreeze effective use period of more than two years, the expiration or found dirty coolant should be replaced. When replacing the old coolant, add clean water, start the engine to idle for ten minutes or so cycle cleaning. Stop the engine and then put the clean water away.

Fill the new coolant should be carried out when the machine is cold, fill the coolant to the highest mark of the reservoir “MAXT” so far, screw the cover to start the engine, idle to the normal temperature of the engine, and then turn off the engine. When the body temperature drops, check the reservoir’s liquid level to maintain the height of the “MAXT. When the body temperature drops, check the reservoir’s fluid level to maintain the “MAXT” position. Otherwise, it should be replenished until enough.

According to the survey, more than 50% of global car engine failure comes from the cooling system! This shows the importance of reasonable matching of antifreeze. Most of the antifreeze sold in the market is made of ethylene glycol as the main raw material. Then, add the right amount of organic or inorganic salts to achieve corrosion and rust prevention.


As the weather turns colder, the water tank is prone to freezing and cracking, and the choice of antifreeze is a top priority for the health of the car’s “heart.”

The full name of antifreeze is automotive antifreeze coolant, which has the function of anti-freezing in winter and anti-boiling in summer, protecting the engine cooling system, improving heat dissipation, and increasing engine efficiency. So, when consumers choose to use automotive antifreeze, what issues should be noted?

The lower the freezing point, the better: the basic indicator of antifreeze is the freezing point and boiling point. Usually, the freezing point of the antifreeze selected should generally be more than 10℃ below the minimum local temperature to prepare for sudden weather changes. For example, the multi-effect antifreeze produced by Great Wall Lubricant has a freezing point range from -25℃ to -50℃, which can meet the demand for vehicle antifreeze in most northern regions of China.

-What specifications of antifreeze should be chosen at -15℃ -25℃, -30℃, -40℃, etc. Generally, it is appropriate to choose one that is more than 10℃ lower than the lowest temperature in the region. In winter, you should choose to use antifreeze with a low freezing point—the lower the freezing point, the stronger the antifreeze performance of the antifreeze. In Beijing, generally choose the freezing point of -30 ℃ antifreeze.

Should pay attention to the anti-corrosion function: there are many types of antifreeze on the market, the quality is inevitably mixed, a generally small blend of antifreeze produced by the factory is only the freezing point of the antifreeze is measured after the market.

Antifreeze is not the purer, the better – first of all, do not directly inject antifreeze mother liquor, antifreeze is not the purer, the better, direct injection of antifreeze mother liquor, there will be antifreeze deterioration, low-temperature viscosity increases, and engine temperature and other phenomena, affecting the service life of the vehicle. Secondly, the engine cooling system must be cleaned before refilling antifreeze. Antifreeze can descale. If added directly, it will allow the shedding of scale to block the water pipes, resulting in poor heat dissipation.

Finally, it should be noted that tap water should not be used to dilute the antifreeze to avoid the reaction between the scale and impurities in the tap water and the additives in the antifreeze, resulting in precipitation.


For those vehicles that run for a long time, such as cabs, generally, high-quality antifreeze is replaced once a year, while those with short running time can be replaced every two years or every 30,000 km. In order to prevent the generation of excessive foam and reduce the heat exchange between the non-antifreeze and engine parts once, confirm that the product is within the validity period when adding it, and for long-lasting antifreeze, the validity period can be up to three years. If you find suspended matter, sediment or deterioration, or discoloration in the antifreeze, you should replace it and clean the system in time.


Before completely replacing the antifreeze, a thorough inspection should be done to see if there are signs of leakage in each pipe and whether there are cracks, focusing on the five-way pipe, which is named because there are five interfaces connecting various parts of the tube. The antifreeze is distributed to different parts of the car after flowing through the five-way pipe. If there is any leakage of antifreeze in this part, the water pipe should be replaced, or the interface should be re-fixed according to the situation.

Drain the water

Drain the old antifreeze and clean the fluid passages with clean water afterward. Add fresh water to the antifreeze refill tank and subsequently fill the tank with freshwater so that it flows continuously through the engine cooling system, followed by idling with the car on for 3 to 5 minutes to allow the water to circulate. At first, the water from the tank is a little light pink. Continue to inject water until the water flowing out is clean. Note don’t forget to remove the heater hose to drain the water from the heater tank.

Change new antifreeze

After draining the water for about 1 hour, add new antifreeze from the water tank (radiator) hose. This is the way to get the antifreeze into the tank quickly. Then add another bucket of antifreeze into the antifreeze tank, add it until the tank is almost full, and hold the car for about 10 minutes, at which time the cooling system drops due to the elimination of some air, then add the antifreeze and fill the tank with the highest mark “MAXT.”

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