Can green coolant be replaced with red?
2 Answers
It can be completely replaced, but they should not be mixed together. If you want to replace green coolant with red coolant, make sure all the green coolant is completely cleaned out. Coolant consists of three parts: water, antifreeze, and additives. Based on the antifreeze component, it can be classified into alcohol-based, glycerol-based, and ethylene glycol-based. Below are detailed introductions: Alcohol-based coolant: Alcohol-based coolant uses ethanol as the antifreeze. It is inexpensive, has good fluidity, and is simple to prepare. However, it has a low boiling point, is prone to evaporation, has an easily rising freezing point, and is flammable. It is gradually being phased out. Glycerol-based coolant: Glycerol-based coolant has a high boiling point, low volatility, is non-flammable, non-toxic, and has low corrosiveness. However, it is not very effective at lowering the freezing point, is costly, and expensive, making it difficult for users to accept. Only a few Nordic countries still use it. Ethylene glycol-based coolant: Ethylene glycol-based coolant uses ethylene glycol as the antifreeze, with small amounts of anti-foaming and anti-corrosion additives added. Since ethylene glycol is easily soluble in water, it can be mixed to achieve various freezing points, with the lowest reaching -68°C. This type of coolant has a high boiling point, low foaming tendency, good viscosity-temperature performance, and anti-corrosion and anti-scaling properties, making it an ideal coolant. Currently, almost all engines and commercially available coolants are ethylene glycol-based.
I also thought about this when I was repairing my car. Why stick to just one color? Actually, the color represents different coolant formulations. Green usually indicates traditional silicate-based coolant, while red often represents Organic Acid Technology (OAT) type. Mixing these two can cause chemical reactions that form precipitates, potentially clogging the water pump and radiator. If you must switch, first completely drain the old coolant and flush the radiator and pipes three times before adding the new red coolant. Never mix them directly to save trouble - my neighbor ruined his engine doing just that last year, costing over 8,000 yuan in repairs. With cars, it's always safer to follow the rules properly.
