How to Winterize Your Car

Battery

Cold weather is the number one killer of car batteries. A battery that works fine in summer can fail on the first cold morning because cold temperatures reduce the battery's available cranking power while simultaneously making the engine harder to turn over (thicker oil, tighter tolerances). The combination is why dead batteries are the number one reason for roadside assistance calls in winter.

What to do:

• Have your battery tested. Most auto parts stores do this for free. The test measures cold cranking amps (CCA) and overall health. If the battery tests weak or marginal, replace it before winter.
• Check the battery terminals for corrosion. White or green buildup on the terminals creates resistance that makes it harder for the battery to deliver power. Clean the terminals with a battery terminal brush or a mixture of baking soda and water.
• If your battery is more than 4 years old, consider replacing it proactively. Most car batteries last 3 to 5 years. A $150 battery is a lot cheaper than a $200 tow truck plus a day of missed work.

Tires

Your tires are the only thing connecting your car to the road. In winter, that connection matters more than ever.

What to do:

• Check tread depth. The legal minimum is 2/32 of an inch, but tires lose significant wet and snow traction below 4/32. Use a quarter: insert it upside down into the tread groove. If you can see the top of Washington's head, the tread is at or below 4/32 and the tire should be replaced before winter.
• Check tire pressure. Tire pressure drops about 1 PSI for every 10-degree drop in temperature. If your tires were set at 35 PSI in 80-degree summer weather, they could be at 30 PSI on a 30-degree morning. Check and adjust pressure monthly in winter. The correct pressure is on the sticker inside the driver's door jamb, not on the tire sidewall.
• Consider winter tires if you live in a cold climate. All-season tires harden in cold weather (below 45 degrees F) and lose grip. Winter tires use a softer compound that stays flexible and grips better on cold, wet, icy, and snowy roads. A set of winter tires on steel wheels costs $400 to $800 and can be swapped on and off each season for years.

Fluids

Coolant (antifreeze). Your cooling system needs a 50/50 mix of coolant and water to prevent freezing. Pure water freezes at 32 degrees F. A 50/50 coolant mix protects down to about -34 degrees F. You can check the freeze point with an inexpensive coolant tester ($5 to $10 at any auto parts store). If the freeze protection is not adequate, the coolant needs to be drained and refilled with the correct mixture.

Windshield washer fluid. Use winter-rated washer fluid that will not freeze. Standard summer washer fluid freezes around 32 degrees F, which means it turns to ice in your washer lines and reservoir on the first cold night. Winter washer fluid is rated to -20 or -30 degrees F and costs the same as the summer stuff. Fill it up before the first freeze.

Oil. Make sure your oil is within the change interval. Cold starts are the hardest on an engine because the oil is thick and takes time to circulate. Fresh oil flows better in the cold than oil that has broken down from heat and mileage. If you are close to your next oil change, do it before winter.

Wipers and Visibility

Winter driving demands good visibility. Snow, slush, salt spray, and shorter daylight hours all reduce how well you can see.

• Wiper blades. If your wipers streak, chatter, or leave unwiped areas, replace them. Blades deteriorate from UV exposure and heat over the summer and often fail right when you need them most. A set of quality wiper blades costs $20 to $50 and takes 5 minutes to install.
• Headlights. Clean foggy or yellowed headlight lenses. Oxidized lenses can reduce light output by 50% or more. Headlight restoration kits ($10 to $20) bring them back to clear. If your headlight bulbs are dim, replace them in pairs so you have even lighting on both sides.
• Defroster. Test your front and rear defrosters before you need them. A defroster that does not work means a fogged-up windshield that you cannot see through. If your defroster is not blowing hot air, the heater core, blend door, or HVAC controls may need attention.

Emergency Kit

Keep these in your car all winter:

• Blanket or sleeping bag
• Flashlight with fresh batteries
• Phone charger (portable battery pack)
• Ice scraper and snow brush
• Jumper cables or a portable jump starter
• Small shovel (folding or compact)
• Bag of cat litter or sand (for traction on ice)
• Bottled water and non-perishable snacks
• First aid kit

You may never need any of it. But if you get stranded on a cold night, every item on this list could matter.