What to Do If Coolant Is Mixed?

[LeMia]

If coolant is mixed, it is best to replace the original coolant. You need to completely drain the coolant from the radiator, flush it thoroughly with purified water, and then refill it with new coolant. You can go to a repair shop for inspection to see if there is any damage and take timely measures to prevent further issues. The replacement cycle for coolant is 2 years or 40,000 to 60,000 kilometers. Long-term failure to replace the coolant can lead to a decline in its quality, reducing its anti-corrosion properties and causing damage to the radiator and pipes. The functions of coolant are: 1. To provide antifreeze protection for the engine and combat low-temperature environments; 2. To prevent the cooling liquid from freezing and cracking the radiator or damaging the engine cylinder block and cylinder head during cold winter parking.

[StClara]

Mixing antifreeze is something you really can't take lightly. I've seen many car owners casually mix different colored antifreezes, resulting in a thick layer of sludge forming in the cooling system, completely clogging the radiator pipes. Just think about it—mixing blue ethylene glycol type with green organic acid type triggers chemical reactions that can lower the boiling point, causing engine temperatures to skyrocket, or worse, corrode metal components. If you've already mixed more than 500ml, I recommend stopping the car immediately and calling for a tow truck. When handling the situation, first drain all the mixed fluid completely, then flush the cooling system three times with a high-pressure cleaner, including small corners like the heater core. Finally, you must refill with new antifreeze of the same brand and color—remember to wait until the engine is completely cool before operating to avoid burns. For daily maintenance, it's advisable to keep a bottle of original antifreeze in the car for emergencies, and never substitute it with other fluids temporarily.

[DeKing]

Mixing antifreeze is not as simple as just adding some water. Combining coolants with different compositions can produce jelly-like sediments. I once found a clogged water pump impeller during a repair. In such cases, handle it in two steps: first, check the mixing ratio. If it's less than 10% of the total fluid volume, you can drive to the repair shop temporarily; but if you've added half a bucket of a different type, you must call for roadside assistance immediately. At the repair shop, have the mechanic thoroughly flush the system with compressed air, then rinse it twice with distilled water and test the pH level. Make it a habit to regularly check the coolant level. If it's low, top it up with the same product. If you can't find the same product, it's better to use distilled water as an emergency measure. Before the season changes, it's best to test the freezing and boiling points. If they're abnormal, the entire coolant should be replaced.

[SanBennett]

I once had a personal experience with mixing coolants. In a hurry to hit the road, I mixed red and blue types, only to have the temperature gauge max out two days later. The mechanic explained that different colors indicate varying chemical formulations—mixing them deactivates additives, raising the freezing point and lowering the boiling point. The solution depends on the mix quantity: if under a liter, drive promptly to a shop for drainage and flushing; large mixtures require immediate shutdown. Flushing is critical—remove the thermostat and circulate clean water for 30 minutes, ensuring all moisture is purged before refilling with fresh coolant. With a shelf life of just two years, sticking to the manual’s replacement schedule is safest; never cut corners by mixing.