The Winter Car Checklist

Nine jobs, most of them under two minutes, done once before the first frost: test the battery, change the washer fluid, replace the wipers, check the tires, treat the door seals, lubricate the locks, buy a cover and a scraper, stock the trunk, and check the lights.

Everything on this list is cheaper, easier and more available in October than in January. That is partly seasonal retail - the good scrapers sell out in the first cold week and the covers that fit your car go first - and partly that a warm garage is a better place to change a battery than a parking lot at 7am.

It is ordered by how much each item saves you, not by how the car is laid out. Do the first three and you have removed most of the problem.

1. Buy a windshield cover

Highest return of anything on this list. Ten seconds the night before removes five to ten minutes of scraping every morning for four months, and it prevents the wipers bonding to the glass if the design covers them.

The only thing that decides which one you can buy is your body panels. Take a fridge magnet to the hood and both front fenders before you order: if it sticks, magnetic covers work; if it slides off, the panels are aluminum or composite and you need straps or door flaps.

The cover picks are here, and if you are not sure the whole category works, the mechanism is explained here. If the car is going to sit rather than be driven this winter, a full car cover is the version of this job that protects the paint as well as the glass.

2. Test the battery

Free, takes five minutes, and it is the difference between replacing a battery on your own schedule and replacing it in a parking lot in January.

Any parts store will load-test a battery at no charge. A load test applies a realistic current draw and measures whether the voltage holds - which tells you something a voltage reading does not.

1. Get it load-tested. If it is marginal, replace it now.
2. Replace anything over four years old that cranks noticeably slower than it used to. Cold does not kill healthy batteries; it exposes the ones that were already going.
3. Clean the terminals with a wire brush and make sure both clamps are tight. Corrosion produces symptoms identical to a dying battery and costs nothing to fix.
4. If the car sits for days at a time and you have power where you park, buy a maintainer. It is the cheapest intervention in this whole guide.

The mechanism behind cold-weather starting failures is in why cars do not start in the cold, and the battery specifications that matter are in the battery roundup.

3. Change the washer fluid

This is the cheapest item on the list and the one that causes the most expensive damage when skipped. Summer washer fluid is mostly water, and water expands when it freezes - in a plastic reservoir, a small electric pump, and thin nylon lines.

The pump is the part that dies, and it is usually behind a wheel liner, so the labor costs more than the component.

You do not need to drain anything. Run the reservoir low by using the washers, then top up with a fluid that has a printed temperature rating at least 20F below your coldest night. Repeat over a couple of weeks and the mix moves toward the winter rating.

The rated fluids are here, and winter vs all-season explains why all-season is a marketing category rather than a specification.

4. Replace the wiper blades

If they are more than a year old, replace them. Rubber degrades from UV, ozone and heat as well as from use, so a blade that spent the summer baking on a windshield is already compromised before winter starts.

The specific winter failure is mechanical: snow packs into the joints of a conventional steel frame and freezes it rigid, so the blade cannot follow the curve of the glass and leaves a smeared arc in your eyeline. Beam blades have no frame for that to happen to.

Blades are fitment parts and the two sides are frequently different lengths on the same car - measure both. The winter blade comparison is here.

5. Check the tires

Two things, and neither takes long.

Tread depth

The classic penny test - insert a penny with Lincoln's head down into the tread groove, and if you can see the top of his head the tread is at or below 2/32 in, which is the legal minimum in most states. For winter driving, 2/32 in is not adequate. Snow traction depends on the tread being deep enough to bite and to clear packed snow out of itself.

Pressure

Tire pressure falls roughly 1 psi for every 10F drop in temperature. That is why the pressure warning light comes on for half the drivers in the country on the first genuinely cold morning - it is gas physics, not a puncture.

Check pressures against the door-jamb sticker, not the number on the tire sidewall, which is a maximum rather than a recommendation. Check them cold, before driving.

If your routes get posted chain control, this is also when to establish whether your owner manual permits chains at all - and whether AWD changes it (it usually does not).

6. Treat the door seals

Ninety seconds a car, once, and it prevents the single most annoying morning of the winter.

A door freezes shut because water sits on the rubber weatherstrip and freezes it to the painted body. Pulling the handle then tears the weatherstrip off the door, which is an expensive repair for a problem a small bottle of silicone conditioner prevents.

1. Pick a dry day in October, before the first freeze.
2. Wipe every door, trunk and hatch seal clean and let it dry.
3. Apply a silicone rubber conditioner to the rubber with a cloth - not to the paint.
4. Reapply through the season per the bottle, especially on doors you use daily.

What to do if it has already happened is in frozen car doors and locks.

7. Lubricate the locks, and find the hidden keyhole

A lock cylinder is a small metal cavity with nowhere for water to drain. Very little water needs to get in for it to freeze solid, which is why a lock can be frozen on a morning when the doors open fine.

• Apply a graphite or PTFE lock lubricant to each cylinder in the fall so water cannot sit on the internals.
• Buy a small lock de-icer and put it in a coat pocket, a bag or by the front door. NOT in the car - that is the one place it cannot help you.
• Find your car's mechanical keyhole now. Almost every keyless car has one, usually under a cap on the driver's door handle, plus a physical key blade hidden inside the fob. Both exist for the day the fob battery dies, and both freeze like any other lock.

8. Stock the trunk

Three problems to equip for: you cannot see out, you cannot move the car, or you cannot leave it. The third is the one prebuilt kits ignore and the one that matters most when it matters at all.

The full reasoning for each item is in what to keep in your car in winter, and whether to buy a bundle or build it yourself is in prebuilt vs DIY.

9. Check the lights, and clean them

Winter is dark at both ends of the commute and road salt films over lenses within days. A headlight covered in salt film puts out dramatically less usable light than a clean one, and nobody notices because it happens gradually.

• Walk around the car with the lights on and check every bulb, including both brake lights, the high-mount brake light and the reverse lights.
• Clean the lenses properly - salt film is not removed by rain.
• Check the rear fog light works if your car has one, since that is exactly what it is for.
• Clear snow off the lights every time you clear the car. Snow-covered tail lights are a common cause of winter rear-end collisions.

What to skip

A checklist that tells you to do everything is a checklist nobody finishes. These are the winter jobs commonly recommended that we would not prioritize:

• Antifreeze testing, unless the coolant is old or the system has been opened. Modern long-life coolant does not degrade quickly, and if the cooling system has not been disturbed the mix is what it was.
• An oil change specifically for winter. Change it on the schedule. What is worth checking is whether the grade is appropriate for your climate - a lower first number, like 0W or 5W, stays thinner when cold - and that is a conversation for the next service rather than a job in itself.
• Winter tires, if you rarely drive in snow. They are the single biggest safety improvement available in snow, and if you get two snowy days a year the storage and swap costs may genuinely not be worth it. Be honest about your own driving.
• Anything sold as a fuel additive for winter starting. Modern gasoline is already winter-blended by the supplier for the season and region.

If you only do three things

1. Buy a windshield cover. It is ten seconds a night against ten minutes a morning, and nothing else on this list has that ratio.
2. Get the battery load-tested. Free, five minutes, and it converts a January surprise into an October decision.
3. Change the washer fluid to something with a printed rating. The cheapest item here, and skipping it is what cracks reservoirs and kills pumps.

Those three take an afternoon between them and remove most of what goes wrong. The rest of the list is genuinely worth doing, and it is the difference between a winter that is fine and a winter you do not think about at all.

Where to go next

• Scrapers and brushes - reach, blade width and the paint question.
• Windshield covers - fastening, wiper coverage and the fridge-magnet test.
• De-icers, washer fluid and wipers - rated temperatures and what the labels commit to.
• Cold starts, batteries and jump starters - cold cranking amps, and the lithium storage rule.
• Emergency kits, traction and recovery - cable gauge, mat length and load ratings.