How to winterize a car

A cold-weather survival guide for your car

Last updated: October 2013

The winter months are hard on your vehicle. Cold temperatures can affect its operation, while dirt and road-salt residue can cause problems with its physical condition. However, there are some simple checks and maintenance items you can do that will help your vehicle stay in top condition.

Good visibility is vital. If your wipers are leaving streaks of water on the windshield, or if the wiper-blade rubber shows any signs of cracking or stiffness, replace them with a new set. (See our wiper blade ratings.) In addition, don't try to use your wipers to remove adhered ice from the windshield; keep an ice scraper in the car for frosty mornings. If the vehicle is parked outside, placing the wipers in the "raised" position before an overnight snow will 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. Be sure to keep your windshield washer reservoir filled with a washer solution that contains an antifreeze agent. Also make sure that 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 other motorists will be able to see you.

Consider a switch to winter tires. If you drive a lot in slippery conditions, it's a good idea to replace summer or all-season tires with a set of dedicated winter tires. These have tread patterns and rubber compounds specially designed to grip snow and ice, for optimum traction on slick roads. Winter tires typically have shorter tread life and generate more road noise than the all-season tires that your vehicle came with. But the extra safety they provide is generally worth the compromise. (See our tire ratings.)

If you'll be using winter tires, you might consider having them mounted on inexpensive steel wheels. This will make it easier to switch between the two sets and it will save your more expensive alloy wheels from the winter conditions.

For extreme conditions, studded snow tires or even tire chains may be warranted. Because they can be tough on road surfaces, check if they're legal in your area before making the investment.

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 zero degrees F, your battery only has about half the cranking power it has at 80 degrees. At the same time, the thickened oil in a cold engine makes it harder to turn over. So the battery is asked to do more while in a weakened condition. Following are a few easy checks to make sure it's in as good condition as possible.

On conventional batteries, remove the plastic caps on top of the battery 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 (check in your owner's manual). If it isn't, have the battery professionally tested at a service station, auto parts store, or repair shop. It may just need to be charged. But if it's defective, it's best to replace it before it goes completely dead. (See our battery Ratings and buying advice.)

The battery cables should be tight enough that they can't be pulled off by hand. If the battery cables and terminals have any white, crusty corrosion forming on them, it can create resistance and reduce the amount of power that can be drawn from the battery. This corrosion can be easily cleaned with a mixture of baking soda and water, which neutralizes the battery acid. Disconnect the battery cables and use an old toothbrush dipped in the mixture to scrub off any corrosion. While the cables are disconnected, it's also a good idea to use a wire brush or a special battery-terminal brush (available at any auto parts store or often in the automotive section of a department store or supermarket) to clean both the terminals and cable connectors. After that, reinstall and tighten the cables so they can't be rotated by hand. Finally, coat the terminals and cable connectors with petroleum jelly or grease to prevent future corrosion.

Make sure you use the right engine oil. Engine oil thickens when cold, making it harder for the engine to turn over. Check your owner's manual for the manufacturer's recommendation, but generally, you should be using a multi-viscosity oil that has a "W" in the viscosity index, signifying that it's formulated for winter use. Typical formulas that are recommended for modern engines include 5W-20, 5W-30, and 10W-30, which provide good oil flow at low temperatures and can usually be used year-round.

Whenever you have the oil changed, also have the oil filter changed to ensure the system has the maximum amount of flow. If you expect to experience extremely low temperatures, you can have an engine block heater installed in the engine. When plugged into a household electrical outlet, it keeps the engine oil from getting cold and thick.

Check your cooling system. Extreme cold can cause rubber parts to become brittle and fail. Check the radiator and heater hoses for cracking, leaking, or contamination from oil or grease. The hoses should be firm yet pliable when you squeeze them. Replace them if they feel brittle or overly soft.

For most vehicles, the cooling system should be flushed at least every two years (check your owner's manual). This helps keep corrosion from building up in the system. If a flush is almost due, have it done before the cold weather hits. The system should be refilled with a mixture of antifreeze and water, typically in a 50/50 ratio. This will keep your coolant from freezing to well below zero. Colder conditions, however, can call for ratios of 60/40 or 70/30. Check your owner's manual or the back of the antifreeze container. Under no circumstances should you use a higher antifreeze-to-water ratio than this.

Prevent freeze-ups. Water can get into door and trunk locks and then freeze, effectively locking you out of the vehicle. To prevent this, lubricate the locks with a silicone spray or door-lock lubricant. If they're already frozen, use a lock antifreeze product to thaw them.

Protection for inside and out. The dirt and salt of winter can also affect your car's paint finish. To help protect it, give the car a fresh coat of wax and then wash it regularly during the winter months. With modern vehicles, corrosion isn't the common problem that it used to be, but it's still a good idea to have the wheelwells and underbody washed regularly to prevent road salt from building up. If your vehicle has alloy wheels, apply a coat of wax to them to help prevent pitting and corrosion.

If you don't already have floormats in your car, you should pick up a pair. Even inexpensive ones will save your car's carpet from the water and mud that tends to get tracked into the vehicle.

Let the engine fully warm up. Condensation in the exhaust system can cause premature rust-through of exhaust components. To help prevent this, try to let the engine reach its full normal operating temperature whenever you drive the vehicle. This will evaporate the moisture in the system. If this isn't possible, try to limit short trips.

By the way, revving the engine excessively when it is cold won't warm it up any faster than just letting it idle normally.

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