Keep the battery in good shape
Your vehicle's battery is especially hard hit when the mercury plummets. Cold temperatures reduce its cranking power. In fact, at about 0° F, a battery has only about half the cranking power it has at 80° F.
To check a conventional battery, remove the plastic caps on the top and check the fluid level. (See your owner's manual.) If the fluid is low, add distilled water. On maintenance-free batteries, check that the window at the top of the battery indicates a fully charged state. If it's more than five years old and shows signs of weakness, replace the battery with a top-rated model.
You can have the battery professionally tested at a service station, auto parts store, or repair shop. A tired battery may just need to be charged. But if it's defective or just worn out, it's best to replace it before it goes completely dead. (Check our buying guide and Ratings for car batteries. Worst case, be sure you know how to jump-start a car.)
Replace wiper blades
You have to replace wiper blades more often than you might think. Our tests have found that even the best-performing wiper blades start to lose their effectiveness in as little as six months. Streaks or missed expanses of glass are sure signs that the blades are ready for retirement.
While it's possible to stretch their life by cleaning the rubber edge of the blade periodically with a paper towel and glass cleaner, it isn't safe to do that all winter long. Instead, get yourself new blades. We recommend replacing wiper blades as often as twice per year. Most wiper blades are easy to install, and some stores, such as Advance Auto Parts, will perform the replacement work free of charge.
Clear the windows
If you can't see out the windows, you're a danger to yourself and everyone around. Don't try to use the wipers and those brand-new wiper blades to remove ice from the windshield. Instead, use an ice scraper on frosty mornings. If you park outside, place the wipers in the raised position when it's going to snow overnight to keep them from freezing to the windshield.
With dirt, mud, and salt residue being kicked up off the road, it's likely that you'll be using your windshield washers a lot, so keep your windshield-washer reservoir filled with a winter-blend washer solution that contains an antifreeze agent.
Also make sure the heater is functioning properly and that plenty of warm air is being directed to the windshield when it's in the defrost mode. To help prevent your windshield from fogging up, run the air-conditioning system (with the temperature set at a comfortable level) to dehumidify the air.
Finally, check that all the vehicle's lights are working properly, so that you'll have optimum visibility at night and motorists front and rear will be able to see you.
To read the rest of this great article go to consumerreports.org