This is the first of several articles about winterizing your car for the cold McHenry season ahead. Today, we’re discussing coolant. Coolant is the liquid that flows between your radiator and engine to keep the latter from overheating. It’s still called upon to do so in the winter, but only after you get going.

Once you’ve driven down the road a while, even if it’s a bitterly cold day or night in McHenry, your engine will produce enough heat that it’s possible to overheat. You still want your coolant to work effectively in this way. But you also want it to perform properly in those times when it’s sitting in the driveway.

In the summer, coolant does just that – it cools the engine during operation by carrying away the heat created by friction within the engine. When the car isn’t running, when the temperature isn’t likely to dip below 50 degrees and, sometimes, not below 80 or 90, the coolant is just fine. It’s sitting there in the engine and radiator waiting for you to start the car again. But things change when winter comes to McHenry.

Consider that water freezes at 32-degrees Fahrenheit. If your coolant froze at the same temperature, you’d have a block of ice in the engine. And when the water freezes, and transforms to a solid, it expands. That expansion can create sufficient pressure to actually crack an iron engine block.

Obviously, it’s essential that the coolant in your engine does not freeze. Doing so is likely to prove extremely costly. And, since the temperature in McHenry will fall well below freezing, sometimes dramatically below freezing, it’s equally essential that the coolant will avoid freezing at even the lowest temperatures.

Your auto repair technician can test your coolant to see at what temperature it will freeze (at the same time, they can let you know when it will overheat). If your coolant doesn’t have the stuff to avoid freezing over the course of a McHenry winter, you want to replace the coolant with coolant that can take whatever winter will throw at it.