In front of your car, truck or SUV engine you’ll find a radiator. Behind the radiator is a fan. The radiator is connected to the engine by hoses – one a supply hose (the lower hose) and the other a return hose (the upper hose). Less visible to the naked eye is a pump, which is part of the engine, that moves the liquid in the radiator and engine in a regular cycle. There’s also a thermostat that can close off the return hose so that the liquid, known as coolant/antifreeze, can reach its peak operating temperature.

The coolant/antifreeze carries away heat from the engine. The fan behind the radiator pulls air through the radiator fins and across the coil of tubes that hold the coolant/antifreeze. As the air passes through the radiator it carries away heat and cools the liquid. In the process, it ensures that the engine doesn’t overheat, which could cause critical damage to parts of the engine.

The engine calls on the coolant to carry heat out to the radiator for cooling all year long though, obviously, the coolant may not have to work as hard during the winter here in Wonder Lake. But, winter poses another challenge for the coolant. That is why we also call it antifreeze.

Even in the winter, friction within the engine of your car, truck or SUV will reach extreme temperatures. But, when the vehicle isn’t running – when it’s sitting in your Wonder Lake driveway, for instance – frigid cold temperatures will make those engine parts so cold that, well, you wouldn’t want to lick them with your tongue – your tongue would stick to them.

That coolant/antifreeze in your Wonder Lake car, truck or SUV engine is very special

The coolant/antifreeze that is used in a car, truck or SUV engine is very special; it’s designed to operate at extremely high temperatures without boiling over and to endure extreme colds without freezing. Plan water can’t compete.

Water boils at 212-degrees Fahrenheit and freezes at 32-degrees. The coolant/antifreeze is designed to endure far greater extremes at both ends of the spectrum. For instance, straight ethylene glycol, an ingredient in coolant/antifreeze, boils at 387-degrees Fahrenheit. With a 50/50 mix, which is customary for use in automobiles, the coolant will boil at 265 degrees (a 50/50 mix is used because the pure ethylene glycol has a greater viscosity – it won’t flow as freely and won’t absorb heat from the engine as readily).

Working as an antifreeze, the liquid is rated to freeze at minus 34-degrees Fahrenheit.

Just as serious damage to the engine and engine parts is possible if an engine overheats, serious damage is possible if the coolant/antifreeze freezes. It’s a matter of physics. Temperature changes cause things to expand and contract. An engine block can crack as a result of the coolant/antifreeze freezing. When that happens, it’s generally time to get a new engine block and engine blocks aren’t inexpensive, especially since you usually don’t merely replace the engine block; you usually replace the entire engine (the engine has parts called ‘freeze plugs’ designed to pop out, hopefully, before an engine block cracks, if the coolant/antifreeze freezes).

Is the coolant/antifreeze in your car, truck or SUV still good?

Over time, the coolant/antifreeze loses its mojo. This means that it will boil at a lower temperature and freeze at a higher temperature. As a result, the engine is more apt to overheat just as the coolant/antifreeze is more likely to freeze on bitter cold days and nights.

Auto parts stores sell inexpensive coolant/antifreeze testers known as hydrometers. These work with some types of coolant/antifreeze by checking the concentration of the chemical in the liquid. With some types of coolant/antifreeze, you’ll need a refractometer to test the ability of the liquid to withstand extremes of hot and cold.

The best bet is to bring your vehicle to a qualified auto repair technician and have them check your coolant/antifreeze. At the same time, they can check for any leaks, such as in the hoses (this includes hoses that run to the heater core, which brings heat into the vehicle cabin so you don’t have to be cold while driving in the winter). They can also check the thermostat to ensure that it opens and closes at appropriate temperatures. They can also check your radiator cap.

Many car owners prefer to change their coolant/antifreeze on a regular schedule. New coolant/antifreeze can last five years or 150,000 miles. But, it is inexpensive enough that it doesn’t really make sense pushing your coolant/antifreeze to the limit. And the peace of mind you’ll receive when facing another cold Wonder Lake winter is, well, priceless.