A typical antifreeze (also called coolant) mixture in a car's cooling system lasts between 30,000 miles and 5 years, whichever comes first. This is the standard interval recommended by most vehicle manufacturers for a complete drain and flush service. However, some modern vehicles equipped with extended-life coolant can have intervals of 100,000 miles or 10 years. The actual lifespan depends heavily on the coolant type, your driving habits, and the vehicle's condition. Relying solely on the color of the coolant is not a reliable indicator of its condition.
The primary reason for replacement is the degradation of the inhibitor package. These additives corrode over time, losing their ability to protect the engine's aluminum, cast iron, and other metal components from corrosion and scale. A failing coolant can lead to expensive damage like a clogged radiator or a failed water pump.
The most reliable way to know if your coolant needs changing is to have it tested. Many auto parts stores offer free coolant test strips that measure the freeze point and the level of additive depletion. If you're unsure of your car's service history, checking the coolant is a simple and wise preventative measure. Always consult your owner's manual for the specific type of coolant and service interval recommended for your vehicle.
| Coolant Type | Typical Service Interval (Miles/Years) | Key Characteristics |
|---|
| Inorganic Acid Technology (IAT) | 30,000 miles / 2 years | Traditional green coolant; older formula. |
| Organic Acid Technology (OAT) | 50,000 miles / 5 years | Common in GM vehicles; often orange or red. |
| Hybrid Organic Acid Technology (HOAT) | 30,000 miles / 5 years | Common in Ford, Chrysler, European cars; often yellow or orange. |
| Phosphate Hybrid Organic Acid Technology (PHOAT) | 100,000 miles / 10 years | Common in Asian vehicles; often red, blue, or pink. |
