Ethylene glycol in concentrated form is highly corrosive, its boiling point is +170°C. Due to the fact that the crystallization temperature of ethylene glycol in concentrated form is -20°C, it is diluted with distilled water to lower the crystallization temperature (tab. 13.1).
To neutralize corrosive activity, special additives are added to ethylene glycol. To distinguish it from other operating fluids and to make it easier to determine the level in the expansion tank of the engine cooling system, a dye is added to the antifreeze.