1. Change your oil
This is something you should be doing when needed, but in the winter months, it’s especially important. You may need to change the type of oil you use altogether. Check your owner's manual to find out what viscosity you should be used in freezing temperatures. Generally, you’ll need a thinner oil in the winter.
2. Check the ratio on your engine coolant (antifreeze)
In normal weather, you typically want a 50/50 ratio of coolant to water but in the winter it should be 60/40.
3. Check your battery
Cold temperatures mean your engine needs more current from the battery in order to start so you want to make sure the battery is functioning properly. Start by making sure you have enough charge left in your battery. The most simple way to check is by turning on your headlights before you start your engine. Then turn your engine on – if the lights get brighter your battery may be dying. You can test the actual voltage at home with a voltmeter or have your mechanic do a test for you. Some batteries also have a built-in hydrometer that measures the voltage. You’ll also want to check the cables for cracks and brakes. Finally, ask your mechanic to check the battery fluid.
4. Change your washer fluid and windshield wipers
Buy a good washer fluid with an antifreeze solution – regular fluids just won’t cut it in freezing temperatures. You should replace your windshield wipers every 6-12 months depending on wear and tear. If they’re starting to look a little haggard be sure to put new ones on before the first big snow storm of the season hits. For especially harsh climates you may also want to pick up a set of winter wipers that protect the wipers’ mechanism.
5. Get a basic tune-up
You should get a tune-up roughly every 30,000 miles. If that tune-up is likely to happen in the winter you may want to go in a little early just to make sure everything is in good shape. Have him or her check your belts and hoses, ignition, brakes, wiring, fan belts, spark plugs, air, fuel and emission filters, and the PCV valve.
6. Check your defroster and heater
These types of repairs can be costly, but you really need your defroster and heater to function properly in order to drive safely in the winter. However, one tip that may save you money on a defroster repair, is to check for air leaks around doors and windows. Leaks can allow in extra moisture that will make it seem like you have a broken defroster.
7. Check your tires
This could mean a couple of different things – you may want to invest in snow tires or just make sure your current tires aren’t too worn out. If you frequently drive in tough conditions in the winter snow tires are a great choice. For particularly perilous conditions you can buy snow tires with studs. If you don’t buy snow tires, you’ll want to check the air pressure on your current tires. Refer to your owner's manual to find out what the pressure should be in the winter. Check your tread for wear and tear as well. Also, remember that if you do skid on an icy road don’t slam on your brakes! Take your foot off the gas and turn it into the skid until you come to a complete stop.
8. Check your 4-wheel drive and know how to use it
This is pretty self-explanatory. You’ll want to know how to use your 4-wheel drive before winter hits.
9. Keep your gas tank filled
I’ve always known that you shouldn’t let your gas tank get all the way to empty in the winter (or any other time for that matter) but never really knew why until today. Apparently, the cold weather can cause condensation to form in an empty or near-empty gas tank. That water can drip down into the gas and sinks to the bottom where it can then travel into your fuel lines. In the winter it can freeze in your fuel lines and block the flow of gas to your engine. Not good! So keep your tank at least a 1/4-1/2 way full at all times.
10. Get your car detailed
This isn’t a completely necessary step but if you’re worried about your car’s paint job it’s a good idea. Don’t forget a car wax that coats the body panels. The wax will help protect the paint from snow and salt damage.
11. Have a de-icer handy at home or in your purse/briefcase
It’s not uncommon for car doors to freeze shut in the winter. You can use warm water if you have access to some or you can buy glycerin to have on hand in an emergency.
12. Beef up your car emergency kit
If you don’t already have an emergency kit in your car now is the time to get one! If you do have one you may want to add a few things for the winter. Jillee has a great post on a DIY first aid kit for the road. In the winter you’ll also want a soft-bristled snow brush, plastic scrapper, kitty litter or salt, a shovel, flashlight and extra batteries, flares, gloves, a coat, snow boots, a couple of blankets, and tire chains (if you’ll be driving in the mountains).