If you leave your car outside at night in freezing weather, and do not take the proper precautions then you might wake up in the morning to find that the reason your car will not start is that the water in the radiator is frozen. Frozen water in the radiator can cause a lot of damage to your entire engine, because when water freezes, it expands. The expansion of the water can actually break the engine block, or (if you are lucky) simply push out a casting plug, more commonly referred to as freeze plugs. This is not a good situation to be in, because if the engine block is cracked from the expanding water, then you will have to replace the entire engine. Also if a freeze plug is pushed out of the engine block, depending on where it is located, you might have to pull the engine out of the car to replace the plug. This can be avoided by using the proper type and mixture of engine coolant (or antifreeze).
If you try to justify not using coolant in your engine with the price of a gallon of coolant being too expensive, then you should compare it to the cost of replacing the entire engine in your car. Common sense would rule here that paying eight dollars for a gallon of antifreeze, is nothing compared to the average cost of replacing an engine which is usually in the neighborhood of two thousand dollars for a used engine to be installed in most cars. If you really do not have the eight dollars for a gallon of engine coolant, then there are some things you can do in order to help prevent the water in your radiator from freezing.
The most important thing you can do, which should be your first line of defense, is to face the front of the car away from the wind. The cold, frozen wind will freeze the water in your cooling system up in just a few hours, just the same as you make ice cubes in your freezer. Putting the vehicle in a garage can also help prevent this from happening, but if you can afford a house with a garage, then you can surely afford a gallon of antifreeze. The next thing you can do is drain the water out of your engine on these freezing nights. After all, if there is no water in the radiator, then it cannot freeze and cause any damage.
Finally, the last line of defense, which is really the only way to eliminate the problem from your life is to use antifreeze in your car's cooling system. Antifreeze takes the freezing point of the coolant in your car from the normal thirty two degree freezing point of plain water to as low as sixty seven degrees below zero. The difference of over ninety degrees in the freezing point of the fluid should speak for itself, on those long cold winter nights. Of course as people we can usually curl up under the blankets with our favorite people to stay warm on those nights. It is almost a shame that your car cannot enjoy the same luxury, with the way it takes care of its people, every day. To sum it up, don't leave your car out in the cold, and treat it like it was a plant or an animal when it comes to freezing weather. You would not be happy to wake up in the morning to a cracked engine block when yuo are due to be at work in 10 minutes.