Can green and red antifreeze be used together?
4 Answers
Green and red antifreeze cannot be used together. The reasons for their different colors are: 1. To distinguish them from other liquids and prevent accidental ingestion; 2. To check the amount of antifreeze added. The full name of antifreeze is antifreeze coolant, which is a coolant with antifreeze function. The components of antifreeze are: inorganic calcium chloride, organic methanol, ethanol, ethylene glycol, glycerin, lubricating oil, and purified water. The main functions of antifreeze are: 1. To provide antifreeze protection for the engine, enabling it to withstand low-temperature environments; 2. To prevent the coolant from freezing and cracking the radiator or damaging the engine cylinder block and cylinder head when parking in cold winters; 3. To provide efficient heat dissipation.
Last time when my car was low on coolant, I temporarily added some green one, while the original was red. After driving for two days, I noticed bubbles in the cooling system. It wasn't until I took it to the repair shop that I realized the trouble I had caused. Coolants of different colors have completely different formulations—green is usually ethylene glycol-based, while red might be Organic Acid Technology (OAT). Mixing them can cause scaling and corrode the radiator. Now, whenever I change the coolant, I strictly stick to the same color and make sure to thoroughly flush the system. If I ever find the level low on the road, I'd rather top it up with distilled water as an emergency measure than mix colors, to avoid ending up like me, spending a fortune on water pump repairs.
Having worked in auto repair for over a decade, I've seen too many cars with problems caused by mixing coolants. The most dangerous is mixing red and green coolants - the additives react to form flocculent precipitates. At best, this clogs small radiator pipes; at worst, it corrodes aluminum alloy engine blocks. Some cars' temperature gauges max out immediately after mixing, requiring costly overhauls costing thousands when towed in. Adding purified water in emergencies is fine, but shouldn't exceed 1/4 of the total volume. I recommend keeping a bottle of the same coolant in your trunk for timely top-ups, avoiding the risks of random emergency additions.
During the first maintenance of a new car, the 4S shop repeatedly emphasized that coolant cannot be mixed in color. Green is a silicate formula, while red contains organic acids. Mixing them will neutralize the additives. Now, during every maintenance session, I make sure to watch the technician use instruments to test the freezing point and pH level. Mixing colors can cause the boiling point to drop, making the car prone to overheating in summer. When buying coolant, always check the certification number against the manual, as different car models have strict formula requirements. Using the wrong mix can even void the warranty.
