Though we don't have to worry about such things down here in Sunny Alabama, Consumer Reports recently ran an article on their website (www.consumerreports.org) listing several major points to consider when "winterizing your vehicle."
Consumer Reports suggests checking wiper blades and replacing them if they leave streaks of water on the windshield or show any signs of "cracking or stiffness." Also, don't ruin your wiper blades trying to remove ice that has formed on the windshield; use a dedicated ice scraper for that. And if the temperature is expected to drop below freezing during the evening, consider leaving your wipers in the raised position overnight to keep them from freezing to the windshield.
Besides your windshield wipers, keep an eye out for other problems that could obscure visibility during the winter season. Periodically check the level of your windshield washer reservoir and keep it filled with a solution that includes some type of antifreeze agent. Ensure that all of your car's lights are working properly so you can see well at night (and so other motorists can see you).
Also, remember to run the air conditioner when defrosting/defogging your windshield. You can set the temperature for whatever you like, but by running the compressor, you dehumidify the air and make it much easier to defrost the glass.
Consider Winter Tires
If you're going to be constantly driving on snow or ice for much of the winter, you might do well to consider swapping your summer or all-season tires with special "winter tires" that feature snow-friendly tread patterns and are made of special rubber compounds that are better suited to grip slick roads. Special studded "snow tires" or even tire chains might be necessary in excessively harsh areas.
CR points out that winter tires usually have a shorter tread life and generate more road noise than other tires, but in many cases, the extra safety they provide far outweighs these nuisances. And if you get tired of having your tires swapped every season or so, you can make the process easier by purchasing a second set of wheels. By mounting your winter tires on a set of cheap steel wheels, you also protect your regular alloy wheels from any damage the harsh winter climate may cause.
Check Your Battery
According to Consumer Reports, a normal battery's cranking power is reduced by almost half when the temperature drops to 0°F. Compounding this problem is the fact that engines are generally more difficult to crank in cold weather, due to thickened oil in the engine.
If your battery is user-serviceable, check the fluid level and top it off with distilled water if necessary. Also, consider having your battery tested (many service stations and automotive shops will do this for free) to make sure it is holding a complete charge. If your battery is on its last legs, you definitely want to replace it now rather than waiting for it to go completely dead.
Also check the cables leading to the battery terminals. These should be nice and tight and free of corrosion. If you spot any corrosion (a white, crusty substance that interferes with the energy transfer between the battery cables and the battery itself), remove it with a toothbrush and a solution of baking soda and water. You may also want to whisk the terminals and cables with a wire brush, available at most automotive stores. (If battery corrosion seems to be a consistent problem with your car, Consumer Reports suggests covering the battery cables and terminals with grease and/or petroleum jelly to prevent future occurrences.)
Check Your Oil
As mentioned earlier, oil thickens in the winter months, making it more difficult to crank the engine. Your car's owner's manual should suggest a suitable winter motor oil, but generally anything with a "W" (which stands for "Winter") in the name is suitable. Common formulas include 5W-20, 5W-30, and 10W-30, which are intended to provide optimum oil flow at low temperatures but (in most places) can be used year-round.
If you live in an area with extremely low temperatures, it might be a good idea to have an engine block heater installed in your car. This is a device you plug in overnight that keeps the engine warm, thus keeping the oil from getting too cold and thick.
Check Your Cooling System
Consumer Reports warns us that "extreme cold can cause rubber parts to become brittle and fail." Make sure your radiator and heater hoses are free of any cracks or leaks. The hoses should be rubbery but firm to the touch. Replace them if anything is out of the ordinary.
Check your car's owner's manual to see how often the cooling system in your car is supposed to be "flushed." If you're due (or, if you've never flushed the radiator at all, as the case may be), try to get this done before the worst of the cold weather hits. Most "quick lube" places will perform this task for around US$50, but there are also a number of DIY kits available from automotive stores, Wal-Marts, etc.
When water gets into door and trunk locks and freezes them tight, use a lock antifreeze agent (again, available at most automotive stores and/or Wal-Mart) to open them. To prevent future freezings, apply a lock lubricant or silicone spray to the keyholes.
Protect your car's finish by giving it a fresh coat of wax and keeping it moderately clean during the winter season. This should prevent dirt and salt (commonly used in deicing roads) from peeling away your paint job. CR also suggests adding a coat of wax to alloy wheels to protect them from corrosion.
Try to limit short trips in the winter months, and when you do drive, allow your car to "warm up" first. Driving before the car is properly warmed up can cause the exhaust system to fill with condensation, which can later cause rust to form on various components. To evaporate the moisture (and thus avoid this problem), allow the engine to run for a short while—until it reaches its normal operating temperature—before you put it in drive. (Don't rev the engine, however, as this does nothing to speed up the process of evaporation.)