Getting a car ready for winter: the autumn checklist

Winter rarely brings a new fault. It brings the old ones forward, all at once: the battery that has been fading for months gives up on the first frosty morning, the wiper that only smeared a little in summer leaves a stripe across your view in slush, and the small paint chip on the bonnet gets salt. Looking in autumn means dealing with the same things, just without the pressure.

Two practical reasons come on top. Some jobs need temperatures that January no longer offers: paint cures badly in the cold, rubber care does not soak into a wet, cold seal, and an underbody wash no longer dries. And as soon as the first snow falls, everyone wants an appointment for tyres, battery and windscreen at the same time — call only then and you wait.

That sets the order of this list. First comes whatever needs a workshop or a part on order: the battery test, the antifreeze reading, a windscreen with a stone chip, the tyre change. Then what you can do yourself in an afternoon: washer fluid, wipers, lights, seals. Last, shortly before the roads are salted, the underbody and the kit in the boot. Tyres, the battery and each country's winter tyre rules have their own articles; this one is about how they fit together.

Coolant is a mix of water and a concentrate that lowers the freezing point and protects the metals in the circuit against corrosion. How far the frost protection reaches depends on the ratio — and that shifts unnoticed if the system was topped up with plain water during the year. Coolant that freezes expands and can damage hoses, the radiator and, at worst, the engine block.

It is measured with an antifreeze tester, either a refractometer or a simple hydrometer; at a workshop it takes a minute. Top up only with the engine cold and only with the type the manufacturer specifies for the car — it is in the handbook. Why types are not mixed and how to recognise a loss is covered in the article on coolant and overheating. If the level drops between two checks, that is not a topping-up matter but a finding.

With washer fluid the mistake is more common and the consequence immediate: summer fluid freezes in the reservoir, the hoses and the jets, and then you are driving through salt spray behind a lorry with no screenwash. Winter concentrate is mixed as the label says, for the lowest temperatures you expect rather than for the autumn afternoon. If a lot of summer mix is still in the reservoir, run it as low as you can first, or what is left dilutes the concentrate. Coolant never goes into the washer reservoir.

Wiper blades age from sun and ozone, and by autumn the rubber has a summer behind it. Smearing, chattering or a stripe that stays mean: replace them, front and rear. Winter adds a rule: never switch the wipers on while they are frozen to the glass. The rubber lip tears and the motor or linkage takes damage. Clear the screen first, then wipe. Many cars have a service position in which the arms can be lifted; how to select it is in the handbook.

In the dark months you drive mornings and evenings without daylight, and lighting stops being a formality. Go through every lamp once, with a second person or in front of a bright wall: dipped and main beam, fog, brake, tail and number plate lamps, indicators. A workshop checks the headlamp aim in a few minutes; after a bulb change or with a heavy load it is often off. Yellowed, dull plastic lenses no longer put the light where it belongs — they can be restored or replaced.

And the glass itself. Misting settles mainly on a film of dirt on the inside, so a thorough clean in autumn pays off. The air-conditioning helps in winter too: it dries the air and clears the glass faster. A clogged cabin filter slows the fan, and wet floor mats keep moisture in the car. A stone chip in the windscreen gets repaired before the frost, not after — temperature swings make it crack, and hot water on an iced-up screen is exactly such a swing.

Cold does not ruin a battery; it shows what state it is in. A cold battery delivers less current while a cold engine with thick oil demands more; what is enough in September is no longer enough in December. That is why the battery test belongs in autumn, and it should be a load test of the kind workshops and many parts shops carry out. A resting voltage reading says little about an ageing battery.

Winter use tightens the sum. Heater, fan, seat and rear screen heating and lights all run at once, often on short trips on which the alternator barely recharges. If you mostly drive short distances, plan a longer drive now and then or put the battery on a charger. The terminals should be clean and tight; white or greenish deposits are a reason to look more closely.

An electric car has a 12-volt battery too, and if it is flat the car stays put however full the traction battery is. The traction battery itself loses range in the cold; preheating the car while it is plugged in takes that energy from the grid rather than from the battery. How a starter battery announces its end, which type belongs in which car and how to jump-start without damage is covered in the article on the starter battery.

Water sitting between the door seal and the frame freezes overnight and glues the door shut. A rubber care stick or spray, applied to dry seals in autumn, keeps them supple and prevents most of it — on every door, the tailgate and the fuel flap. If a door is frozen anyway, do not pull hard: the seal tears and the damage stays. Pushing firmly against the door often breaks the ice; otherwise try another door.

If you still unlock with a key in the door, keep lock de-icer ready — in your coat pocket or in the house, not in the glovebox of the car you want to open with it. A drop of lock lubricant in autumn keeps moisture out of the cylinder. On cars with a remote key, check the coin cell in the key instead: it weakens in the cold, and how to open and start the car with a flat key battery is in the handbook.

The most important item in this section is the underbody. Road salt needs moisture to act, and finds it wherever dirt holds it: in the wheel arches, on the sills, in seams and cavities. Before the salt season, then, the underbody and wheel arches get a thorough wash, dirt deposits are removed, and the drain holes in doors and sills and the water drain below the windscreen are cleared of leaves. That is also when you see whether the protective coating has gaps and whether paint chips are open — both get sealed while it is still dry and mild.

During the winter itself: a wash with an underbody programme after long salty spells, especially in a thaw, and a thorough one in spring. Where rust starts first and which spots decide the car's substance is covered in the article on rust.

Two habits first. In winter the tank is not run down to reserve: stuck on a closed road, you will be glad of every quarter of an hour of heating. And snow comes off the whole car before you drive, the roof included — otherwise it slides onto the windscreen at the first brake or flies at the vehicle behind, which some countries also penalise. If you drive a diesel and set off from a mild region into the cold, fill up at your destination: in the cold season filling stations sell diesel in a more cold-resistant grade.

What has to be carried in a given country anyway, such as a hi-vis vest or a warning triangle, is national law; the motoring clubs publish current lists, and the same goes for winter tyre rules.

Beyond that, winter kit is not a question of quantity but of the situations it covers: an iced-up car in the morning, a flat battery in a car park, a closed road where you sit for an hour. For each of them there are one or two things that make the difference: