There are actually many types of automotive coolant. From my driving experience, the common ones mainly fall into three categories: The first is the traditional green coolant, called IAT, which uses inorganic additives. Older cars often use it, and it generally needs to be replaced every two to three years; otherwise, the anti-corrosion effect deteriorates. The second is the orange or red OAT coolant, which uses organic acid technology for long-lasting anti-corrosion and can last five to seven years. Newer cars mostly use this type for convenience. The third is the blue or yellow HOAT, a hybrid technology that combines the advantages of the first two, with a moderate lifespan. Different colors represent different formulations—never mix them, as doing so can cause foaming, clog pipes, and corrode components. I've seen cases where someone tried to save money by mixing coolants and ended up damaging the water pump. There are also pre-mixed and concentrated versions; concentrated coolant must be diluted with distilled water—don’t use tap water to avoid scaling. When choosing coolant, always match the type specified in the manual—don’t cheap out and buy low-quality products. Regularly check the fluid level and color changes to prevent the cooling system from overheating or bursting. The key function of coolant is freeze and boil protection, which safeguards engine longevity.
