Coolant is often overlooked until it’s absolutely necessary or too late. Also known as antifreeze, it is a bright green or yellow liquid that is normally mixed 50/50 with water to keep your radiator from overheating or freezing.

Two Forms

Coolant comes in two forms ethylene glycol and propylene glycol and is well suited depending on where you live and your lifestyle.

Ethylene glycol – With having a lower freezing point and lower viscosity it is better for colder climates or locations with more severe winters. With a low flammability, it won’t ignite inside your radiator due to high heats. This compound on its own biodegrades in 10-30 days in its pure form. Ethylene glycol is a mild skin irritant but toxic if exposure to skin and highly toxic if ingested although it’s not carcinogenic.

Propylene Glycol – With having a higher boiling point and higher viscosity it is better for hotter climates or locations with more severe summers. With a low flammability, it won’t ignite inside your radiator due to high heats. This compound on its own biodegrades in more than 20-30 days in its pure form. Propylene glycol is a mild skin irritant but toxic if consumed in large quantities although it’s not carcinogenic. Mixes with propylene glycol are a safer option if you have children and pets around.

How it Works

Coolant changes both the boiling and freezing point of water in your radiator. Water alone freezes at 32 degrees Fahrenheit and boils at 212 degrees Fahrenheit. Normal operations of your engine can easily reach the boiling point of water and the inverse can be said about when your car is off in the winter. To combat this coolant is mixed in, as previously mentioned, at a 50/50 ratio. For example, with a 50/50 mix of coolant and water, the new boiling point would be around 223 degrees Fahrenheit. Whereas, The new freezing point of coolant would drop to around -35 degrees Fahrenheit. This temperature flexible liquid allows your vehicle not to cook in the summers and for the liquids not to freeze in the winters.

When to Change

In most cases the manual of your vehicle lets you know the appropriate times to change your coolant and is mainly advised to be changed every 30,000 miles. In other makes and models, this information is left out from the manual altogether. With newer models, they are subject to higher environmental regulations making them more efficient and making coolant last longer. If ever unsure or in doubt, you should consult a certified mechanic to perform a check and give you the information needed.

If you’re more of a person to check their own coolant then check out this related article: Self-Check: Six Fluids Guide.

What can affect the life of the coolant?

Make & Model – As previously mentioned newer vehicles are more efficient and deteriorate coolant slower than older models. This is due to higher environmental regulations for auto dealers and manufacturers. Older models when made were not subject to the same regulations and often require more coolant.

Wear & Use – Various action apart from normal commute can reduce the life of coolant significantly. If your vehicle is used mainly for towing or racing you put more of a strain on your engine and generate more heat in the engine.

Time – As stated before both forms of coolant biodegrade over time. This causes the coolant to become more acidic and lose its rust-inhibiting properties. Rust is corrosive to practically all parts of the radiator such as the water pump, caps, thermostat, hoses, etc. A failing radiator can cause the engine to overheat.

The radiator is one of the most essential components of your engine. Between keeping your vehicle from freezing in the winters to overheating int he summers it should be well maintained. Time, wear, use, make & model all play a factor in your changing schedule and should never be overlooked. Always consult a certified mechanic for they are professionals and will give you the care you need.