Mechanical failure, an inconvenience anytime it occurs, can be deadly in the winter. Preventive maintenance is a must. Besides, a well-maintained vehicle is more enjoyable to drive, lasts longer, and could command a higher resale price.
Some of the following tips can be performed by any do-it-yourselfer; others require the skilled hands of a professional auto technician.
Engine performance - Get engine driveability problems (hard starts, rough idling, stalling, diminished power, etc.) corrected at a good repair shop. Cold weather makes existing problems worse. Replace dirty filters-air, fuel, etc.
Fuel - Put a bottle of fuel de-icer in your tank once a month to help keep moisture from freezing in the fuel line. Note that a full gas tank helps keep moisture from forming.
Oil - Change your oil and oil filter as specified in your manual; more often (every 3,000 miles) if your driving is mostly stop-and-go or consists of frequent short trips.
Cooling systems - The cooling system should be completely flushed and refilled about every 24 months. The level, condition, and concentration of the coolant should be checked periodically. (A 50/50 mix of antifreeze and water is usually recommended.) DIYers, never remove the radiator cap until the engine has thoroughly cooled! The tightness and condition of drive belts, clamps, and hoses should be checked by a pro.
Windshield wipers - Replace old blades. If your climate is harsh, purchase rubber-clad (winter) blades to fight ice build-up. Stock up on windshield washer solvent-you'll be surprised how much you use. Carry an ice-scraper.
Heater/defroster - The heater and defroster must be in good working condition for passenger comfort and driver visibility. Newer models have a cabin air filter that should be replaced periodically. Check your owner's manual for the location and replacement interval.
Battery - The only accurate way to detect a weak battery is with professional equipment. Routine care: Scrape away corrosion from posts and cable connections; clean all surfaces; re-tighten all connections. If battery caps are removable, check fluid level monthly. Avoid contact with corrosive deposits and battery acid. Wear eye protection and rubber gloves.
Lights - Inspect all lights and bulbs; replace burned out bulbs; periodically clean road grime from all lenses. To prevent scratching, never use a dry rag.
Exhaust system - Your vehicle should be placed on a lift and the exhaust system examined for leaks. The trunk and floorboards should be inspected for small holes. Exhaust fumes can be deadly.
Tires - Worn tires will be of little use in winter weather. Examine tires for remaining tread life, uneven wearing, and cupping; check the sidewalls for cuts and nicks. Check tire pressures once a month. Check the tires when they are cold before driving for any distance. Rotate as recommended. Don't forget your spare, and be sure the jack is in good condition.
Carry emergency gear: gloves, boots, blankets, flares, a small shovel, sand or kitty litter, tire chains, and a flashlight. Put a few "high-energy" snacks in your glove box.