How Long Does Coolant Last In A Car?

Antifreeze, commonly called coolant, is a bright yellow or green liquid that prevents the cooling system from overheating or chilling when combined with the water in the car, truck, or other vehicle.

With the addition of additives, coolant, typically comprised of water and antifreeze, can possess several properties that enhance its performance. For instance, a corrosion inhibitor is often introduced to the coolant to prevent rust on the metallic surfaces of the engine. Such additives will deteriorate over time as the fluid becomes increasingly acidic.

This degraded liquid can cause severe damage to your engine if the temperature is not regulated correctly. Therefore, manufacturers recommend periodically replacing the refrigerant. Changing the coolant is advised after the first 140,000 miles (210,000 km) or 120 months, and then every 30,000 km (20,000 miles) or 24 months after that.

How Often to Change the Engine Coolant?

When should you replace your engine’s coolant? It would be best to replace the coolant in some cars every 30,000 miles. For some, its replacement is not even on their servicing schedule.

For instance, Hyundai recommends replacing the coolant (“antifreeze”) in most of its cars after the initial 60,000 miles and then every 30,000 miles. On certain Mercedes-Benz cars with specific engines, the time frame is every 30,000 miles, while on others, it is every 120,000 miles/ 12 years. On other Mercedes, the replacement interval is 15 years or 150,000, whichever comes first.

On automobiles subjected to “severe work,” for example, regular pulling, which can produce more heat, some manufacturers advise draining and flushing the cooling system and replacing the coolant more frequently. Despite how the vehicle is driven, however, the routine for most Chevrolets necessitates a change at 150,000 miles.

However, many repair shops, including dealers selling vehicles with “lifetime” coolant, affirm that one must replace the coolant more frequently than the service plan specifies, for instance, 30,000 to 50,000 miles.

Most cars use long-life radiator coolant, which, without maintenance, can safeguard against freezing in wintertime and boiling in the summer for several years. This coolant is typically a 50/50 blend of antifreeze and water. Environmental regulators have pressured manufacturers to decrease the volume of old coolant and other waste fluids that must be discarded or recycled. As a result, today’s cars have a longer span between coolant and oil changes.

Coolant can degrade over a period of time and must be examined to determine if it is still effective, as it can be difficult to tell based on appearance alone. Even if the reservoir indicates a sufficient level of coolant and testing suggests that the antifreeze and cooling protection are still okay, a coolant discharge and antifreeze rinse may be required.

Over time, the antifreeze can get more corrosive and lose its rust-preventing properties, leading to corrosion. Corrosion can cause damage to the radiator, water pump, radiator cap, thermostat, tubing, and other components of the vehicle’s ventilation and heating systems. And this can lead to engine overheating.

Therefore, the refrigerant in any car with over approximately 50,000 miles must be regularly replaced. Even if the cooling system appears to be functioning correctly and the reservoir is full, this is to check for rust and leakage and to ensure that it has adequate cooling and overheating protection. The cooling system can be examined with test samples that measure acidity and a hydrometer that gauges freezing and boiling protection.

If the rust inhibitors have degraded, it is necessary to replace the coolant. Regardless of the maintenance schedule or the number of miles on the odometer, it could prove necessary to drain the cooling system to eliminate contaminants. If testing reveals that the antifreeze is still protecting against overheating and preventing corrosion, replacing it more frequently than the maker advises might prove a waste of money.

Does Engine Coolant Deteriorate Over Time?

Yes, coolant can degrade with time. Coolant is a combination of antifreeze and water used to prevent overheating in car engines. It can become tainted with grime, rust, and other debris over time, diminishing its efficacy.

Heat and extended oxygen exposure can also degrade specific additives within the coolant, diminishing its capacity to protect the engine from overheating and freezing.

Thermal breakdown causes the coolant to disintegrate into compounds, many of which are harmful to the water pump and other engine parts. This degradation can be expedited by debris and contaminants confined inside the cooling system, as they act as abrasives over time and hasten the coolant’s breakdown.

Oxidation can occur when oxygen interacts with the coolant, further degrading the coolant and reducing its effectiveness over time. Additionally, water pumps tend to leak, letting dirt and metal fragments into the system, polluting the coolant and lowering its performance.

How to Know if Coolant Has Gone Bad?

If the coolant appears to have rust in it or has turned brown rather than the bright green or orange color it was initially, you should have the coolant purged. If the coolant passages in the radiator are clogged, this is also an indication that the antifreeze needs to be replaced.

To determine when antifreeze has gone rancid, you must observe any changes in its chemical and physical characteristics. If the coolant gets viscous or cloudy, it may have gone wrong.

In addition, if the coolant has a foul odor or its color changes, these are signs that it has gone wrong. One can also use a refractometer or hydrometer to verify its specific gravity and decide whether or not the coolant needs to be replenished.

In addition, it is essential to evaluate the pH level of the antifreeze using a pH test device. If the pH level is less than 7, the coolant becomes contaminated. Lastly, recurrent overheating issues and an unexpected rise in the temperature gauge indicate a deteriorating coolant.

If these signs are present, the antifreeze is degraded and must be replaced.

How Long Does Coolant Last Depending on Its Color?

Blue and green

Historically, green and blue symbolized Inorganic Additive Technology (IAT) coolants. This form of outdated antifreeze contained silicates and phosphates and required replacement on average every two years.

Orange and Red

Orange and red coolants were classified as Extended Life Coolants (ELC) and had an extended shift interval than IAT variants, typically up to five years or one hundred thousand miles. They use corrosion-inhibiting additives and antimicrobial compounds to reduce engine wear and enhance protection.


It is compatible with G13, a more recent coolant type used in modern automobiles, and it is a synthetic, advanced radiator coolant that lowers the heat of your car’s engine by increasing heat transmission. It inhibits the formation of mineral deposits in a radiator, optimizing the coolant flow. The purple coolant has a lifespan of three to five years or one hundred fifty thousand miles.

Other Antifreeze/Coolant Colors

Although yellow, blue, orange, and red are among the most prevalent colors for coolant and antifreeze, you may also encounter purple, pink, and turquoise. These colors may be linked with various chemical compounds, such as Hybrid Organic Acid Technology (HOAT) phosphate coolant. Still, as stated previously, the color does not necessarily reflect the fluid’s composition.


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