Let’s start with the simplest – the color of antifreeze. The blue color of just made antifreeze is due to the addition of the dye. Under certain temperature and lifespan, dye starts to change color from blue to green, and after a while becomes colorless. Comparing the color of worked antifreeze with the results of its laboratory tests and the state of the cooling system the following relationship has been established. When antifreeze was blue, corrosion of parts in operation has only been observed in 28% of the cars.
Another important indicator is the density of the antifreeze. From it, you can judge about the temperature of crystallization of antifreeze. The concentration of ethylene glycol plays also a significant role in the protection against corrosion of the cooling system. Thus, 83% of the cooling system where coolant density was less than 1.075 g / cm3, the corrosion of parts was observed. The same results were obtained on the metal samples in laboratory tests. In order to ensure a normal life of antifreeze and good protection against corrosion of the cooling system, it is necessary to keep the antifreeze concentration not lower than 50%, which corresponds to a density of 1.075 g / cm3 at 20 degrees Celsius.