16 Winter Driving Mistakes That Wreck Your Car

Cold Weather Is Hardest on Cars in Ways You Don't See

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Winter does not break most cars all at once. It chips away at the parts that were already tired, then picks one cold morning to finish them off. A battery that started the engine all summer can lose a large share of its strength as temperatures fall, and AAA clubs commonly put the loss around 35 percent at 32 degrees and roughly 60 percent at zero. At the same time, engine oil thickens, which makes the engine harder to turn over, and rubber in tires, wipers and hoses stiffens and cracks. Salt and slush work on the underside of the car for months, and a frozen windshield tempts drivers into shortcuts that cause real damage. Most of the mistakes below are habits, not repairs, which means they cost nothing to fix. Others are small maintenance jobs that are far cheaper in October than on the shoulder in January. Start with the owner's manual, since it lists the correct fluids, tire pressure and service intervals for your exact vehicle.

Waiting for the Battery to Fail

Batteries rarely announce their death in warm weather, and then a cold snap exposes them. Cold slows the chemical reaction inside a lead-acid battery while the engine demands more power to turn thick oil, so a battery with only a little life left can fail on the first freezing morning. AAA recommends having the battery and charging system tested if the battery is more than three years old, and many shops will do it for free. Warning signs include slow cranking, dim headlights at idle and a battery warning light. Look at the terminals as well, since white or blue crusty corrosion can choke the connection, and a wire brush plus a tightened clamp is often the whole fix. Check the date code on the case, which usually shows when the battery was made. Replacing a tired battery on your schedule costs far less than a tow, and a compact jump starter in the trunk is a smart backup. Short trips that never let the alternator catch up shorten battery life even further.

Ignoring Tire Pressure as Temperatures Drop

Air contracts as it cools, and tire pressure falls with it. The rule of thumb is about one pound per square inch for every 10 degrees of temperature drop, though some AAA clubs say it can be one to two pounds. That means a tire set properly in September can be four or five pounds low on a freezing January morning. Underinflated tires wear unevenly, hurt fuel economy, handle sluggishly and are more likely to be damaged by potholes. Use the pressure printed on the sticker inside the driver's door jamb, not the maximum number molded into the sidewall. Check pressure when the tires are cold, before you drive, and top them up at home or a gas station. The tire pressure warning light often comes on at the first cold snap, and it is a signal to act, not to ignore. A decent pocket gauge costs under ten dollars and is more reliable than many gas station gauges. Do not let air out of a tire that reads high after a long drive, because heat inflates the reading.

Running Worn or Summer Tires on Snow

Tires are the only part of the car that touch the road, and in winter their condition matters more than the number of driven wheels. Summer performance tires stiffen in the cold and lose grip dramatically, and even all-season tires can lose bite once temperatures fall below roughly 45 degrees. Tread depth matters too, and AAA suggests at least 4/32 of an inch for winter driving, compared with the legal minimum of 2/32 in most states. A quick check is the quarter test: insert a quarter upside down into a tread groove, and if the top of Washington's head is visible, the tread is thin. Dedicated winter tires use softer rubber compounds and deeper siping that stay flexible in the cold, and independent testing has repeatedly shown shorter stopping distances on ice and snow than all-seasons. Look for the three-peak mountain snowflake symbol on the sidewall. Fitting all four tires matters, since mixing winter tires on one axle can make the car unstable. If your region only sees occasional snow, good all-seasons in good condition are often enough.

Idling the Engine for Ten Minutes to Warm It Up

Idling in the driveway while you finish your coffee feels responsible, but on a modern fuel-injected car it is mostly wasted fuel. Engines warm up faster under a light load than at idle, so the standard advice from many automakers and the Department of Energy is to drive gently after about 30 seconds. Long idling burns fuel, adds engine wear because the extra fuel can wash oil from cylinder walls, and produces emissions for no benefit. What you do need is visibility, so clear all the snow and frost from the windows before you move. Drive gently for the first few miles, keeping the revs low until the temperature gauge starts to climb. Older carbureted vehicles, diesel trucks and some turbocharged engines have different needs, so check the manual for guidance. Remote starters are fine for comfort, but they are not a mechanical necessity. Never idle in a closed garage, because carbon monoxide builds quickly and is deadly.

Driving Around With the Tank Near Empty

A low fuel tank in winter is a bad bet for two reasons. First, if a storm closes the highway and leaves you stuck for hours, running the engine intermittently for heat is the only thing keeping you warm, and that takes fuel. Second, a partly empty tank has more air space, which allows moisture to condense inside, and water in the fuel system can freeze in fuel lines. Gas-line antifreeze products, which are mostly alcohol-based, are sold for this reason, but the simplest solution is to keep the tank at least half full in cold months. Many drivers adopt a rule of filling up as soon as the gauge hits half. That habit also protects the fuel pump, which uses gasoline to stay cool. If you do get stuck, clear the exhaust pipe of snow before you run the engine, because a blocked tailpipe can send carbon monoxide into the cabin. Run the engine for short periods and crack a window slightly.

Using Cruise Control on Wet or Icy Roads

Cruise control is a convenience that depends on the tires keeping their grip, which is exactly what winter takes away. If the car hits a patch of ice or slush while cruise is engaged, the system can try to maintain speed by sending power to the wheels, and a spinning drive wheel can quickly turn into a skid. Drivers also lose a few moments reacting, because their foot is no longer on the pedal. Safety agencies and most owner's manuals advise turning cruise control off in rain, snow, ice and any condition where traction is uncertain. Driving manually keeps you attuned to the feel of the road, so you notice a light steering or a loose rear end before it becomes a slide. Adaptive cruise systems add radar and braking, but they still rely on cameras and sensors that can be blinded by snow or road spray. Drive with smooth, gentle inputs, and slow down before curves, bridges and overpasses, which freeze first.

Slamming the Brakes When the Car Slides

Panic braking is the instinct that turns a small slide into a crash. On ice, hard braking locks the wheels or triggers the anti-lock system, and a car with locked front wheels does not steer. If your car has ABS, which every modern vehicle does, press the brake pedal firmly and keep steady pressure, and feel the pedal pulse as the system works. Do not pump the brakes, which is the old technique for cars without ABS. Look and steer where you want to go, not at the obstacle, and ease off the accelerator in a skid. For front-wheel skids, lift off the gas and let the tires regain traction before you steer. Rear-wheel skids call for steering gently in the direction the back end is sliding. The best defense is smooth driving: brake early, brake lightly, and brake in a straight line before the turn. An empty parking lot after a snowfall is a good place to practice how your car behaves.

Following Too Closely

The three-second rule that works in summer is not enough on snow. Stopping distances on packed snow and ice can be many times longer than on dry pavement, and safety groups often cite up to ten times on ice. At 30 miles per hour, a car on dry road may need about 75 feet to stop, while a car on ice can need several hundred. Winter driving instructors recommend increasing following distance to eight to ten seconds when conditions are poor. Watch for brake lights several cars ahead, since sudden stops cause pileups. Heavy trucks need even more room, and a bright spray from a plow can reduce visibility sharply, so stay well back from plows and sanders. Keep your lights on, which also turns on taillights in most vehicles, so you are visible. If the vehicle behind you is tailgating, increase your own space in front to allow gentler braking. Slower is not just safer, it is also what lets your tires keep grip.

Pouring Hot Water on a Frozen Windshield

It is the fastest shortcut and one of the most common ways to crack a windshield. Glass expands and contracts with temperature, and when scalding water hits cold glass, the sudden difference can cause thermal shock. A tiny chip that was invisible yesterday can turn into a crack across the glass. Safer options include running the defroster for a few minutes before scraping, using a plastic ice scraper with a brush, or spraying a de-icer. You can make a homemade de-icer by mixing two parts isopropyl alcohol with one part water in a spray bottle, which lowers the freezing point. Park facing east where the morning sun can help, or cover the windshield with a sheet of cardboard or a purpose-made cover the night before. Do not use metal tools on the glass, and avoid pulling frozen wiper blades off the glass, since the rubber can tear. Clear every window fully, including mirrors, rear glass and lights, before you drive.

Filling the Reservoir With Summer Washer Fluid

Winter roads throw salt and slush onto the windshield, and drivers use far more washer fluid than they expect. Summer or water-only fluid can freeze in the lines, leaving you blind behind a truck's spray. Use fluid rated for low temperatures, which is typically labeled for minus 20 degrees or colder, and check the label for the lowest temperature. If you have leftover summer fluid, top it off with winter fluid to dilute it, or use it up before the first frost. Do not substitute coolant or antifreeze, which is toxic and can damage paint and rubber. Check the nozzles for ice and make sure they spray in the correct pattern, since heated nozzles on some cars still need clear holes. Carry a spare jug in the trunk, because a long storm can empty the reservoir in an hour. Remember that a dirty windshield creates glare from low winter sun, so keep the inside glass clean as well, which reduces fogging.

Putting Off Wiper Blade Replacement

Wiper blades do the most work when you can least afford them to fail. Rubber hardens in the cold and degrades from sunlight, so blades that were fine in spring can streak, chatter or leave bare patches by November. Most manufacturers recommend replacing blades every six to twelve months, and a set costs far less than the safety they provide. Winter blades have a rubber boot around the frame, which stops ice from clogging the hinges, and they perform better in snow than standard blades. Lift the wipers off the glass when snow or ice is forecast, so they do not freeze in place, and never run a wiper that is stuck to the glass, since it can burn out the motor. Clean blades with a damp cloth to remove grit. If your wipers leave a haze, check the windshield itself for built-up residue, and consider a rain-repellent coating, which helps ice shed more easily.

Letting Road Salt Sit on the Undercarriage

Road salt is a bargain for safe roads and a slow disaster for steel. Salt and brine speed up corrosion on frames, brake lines, fuel lines, exhaust parts and suspension components, especially when mixed with slush that stays packed in crevices. Cars in the Snow Belt are known for rusting out in a decade or less if not cared for. The cure is washing the vehicle regularly in winter, including the undercarriage, ideally on days when temperatures climb above freezing so the water does not freeze in locks and door seals. Many car washes offer an undercarriage rinse for a small charge. Wax or sealant before winter gives the paint extra protection, and a fluid-film undercoating can help on trucks and older vehicles. After washing, dry the door seals and lubricate them with silicone spray to stop them freezing shut. Inspect brake lines and frame rails in spring, and repair rust spots while they are small, before they become structural.

Driving Off With Snow on the Roof

Clearing only a peephole in the windshield is a habit that endangers other drivers. Snow and ice left on the roof, hood and trunk can slide onto the windshield when you brake, blocking your vision, or fly off at highway speed and strike the car behind. Ice sheets from trucks and SUVs have caused serious accidents. Several states, including New Jersey and Pennsylvania, have laws that allow fines when ice or snow flying from a vehicle injures someone or damages property. A foam snow broom with an extendable handle makes the job quick and protects the paint. Clear the headlights, taillights, mirrors, side windows and license plate as well, since being visible is half the battle. Push snow away from the car, not onto the sunroof seals. If you cannot reach the roof, a step stool or a long-handled brush helps, and a brief stop in the garage before leaving can save a lot of grief later.

Skipping the Winter Emergency Kit

Most winter emergencies are not dramatic, just slow and cold: a slide into a ditch, a closed highway or a dead battery far from help. A basic kit turns those into inconveniences. Pack a warm blanket or sleeping bag, spare gloves and a hat, a small shovel, an ice scraper, a flashlight with fresh batteries, and jumper cables or a jump starter. Add a bag of sand or cat litter for traction, a tow strap, a first aid kit and a phone charger or power bank. Keep non-perishable snacks and bottled water, though be aware that water can freeze, so a few energy bars are more reliable. Reflective triangles or flares help other drivers see you in a snowstorm. Store the kit in a bin that stays secured in the trunk or cargo area. Review the contents each fall, replace expired items and let someone know your route and arrival time on long trips.

Neglecting the Coolant Mix

Antifreeze does more than keep the radiator from freezing. It raises the boiling point, protects against corrosion and lubricates the water pump, which is why a weak mix can cause trouble even in winter. A 50/50 mix of coolant and distilled water typically protects against freezing down to around minus 34 degrees Fahrenheit, but the mix weakens over time as additives wear out. Frozen coolant can crack the radiator, hoses and even the engine block, a repair that can cost thousands. A cheap hydrometer or test strips at an auto parts store can check the freeze protection in minutes. Make sure to use the type specified in your owner's manual, since mixing incompatible coolants can create sludge, and colors do not reliably indicate chemistry. Check the level only when the engine is cold, because the system is pressurized and hot coolant can cause serious burns. If the level keeps dropping, have the system checked for leaks, and flush it at the interval your manufacturer recommends.

Setting the Parking Brake in Freezing Weather

The parking brake is a good habit most of the year, but in very cold, wet conditions it can freeze in place. If moisture gets into the cable or the brake pads and shoes and freezes overnight, the brake may not release in the morning, and forcing it can damage the cable or the drum. This risk is highest after driving through slush or running a car wash, when the system is wet and then cold. For automatics, the transmission's parking pawl holds the car on flat ground, so you can leave the brake off in extreme cold. On hills, turn the front wheels toward the curb and use wheel chocks if you are worried. Drivers of manual cars can leave the vehicle in gear. If the brake does freeze, let the car warm up, use a gentle application of heat or de-icer, and avoid driving with the brake partly engaged. Check your manual for specific advice.

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