Coolant or antifreeze has existed for about 100 years, since the invention of water cooled engines. Originally, many other liquids were proposed to customers as antifreeze: pure water, salt solutions, alcohols and even… honey! However, in the 30-ties of the last century the role of coolant began to play ethylene glycol. Apropos the first antifreeze based on ethylene glycol was created by BASF – a German chemical concern. And in the 40-ties the special anti-corrosion and anti-foaming agents (inhibitors) were invented.
There is no unified standard for antifreeze. Thus a single classification, established by VW, is used. All antifreeze liquids are divided into G11, G12 and G12 plus groups. The classification depends on what additives and in what quantities are present in the coolant. G11 antifreeze has blue or green color and is required to be changed every 2 years. G12 antifreeze is usually red, pink or purple and its life is about 4-5 years. It is important to remember, that G11 and G12 grades should never be mixed together. Finally, G12 plus coolant has a pink color, can serve for 4-5 years and can be mixed with other antifreeze.
Surprisingly, most modern antifreeze hasn’t been changed for the last 30-40 years. These liquids consist of ethylene glycol, diluted with water and additives. 1:1 ratio of ethylene glycol and water freezes at -36 degrees. Such mixture doesn’t form solid crystals and turns into a kind of jelly, which protects the pipes of the cooling system even in severe frost. If the concentration of ethylene glycol to water is 2:1, such mixtures doesn’t freeze up to -65 deg. C. And the boiling temperature reaches 105-110 degrees.
A real breakthrough in the market of antifreeze occurred recently – in the 90-ties. A new antifreeze based on carboxylic acids was found. In addition to better metal protection properties, these coolants are distinguished by the vitality of its operational parameters. 5 years of service is a rule for this antifreeze without any exceptions. However, in spite of complete absence of nitrites, silicates, phosphates and other agents, such coolants are not compatible with antifreeze based on ethylene glycol.