Winter visibility checklist: wipers, screenwash and lights

Most of it is quick to do on a dry weekend, and the clocks going back on the last Sunday of October is a good reminder to do it before the dark evenings arrive.

Your winter visibility checklist

What screenwash should I use in winter?

Use a screenwash that is made for winter and mix it at the strength the bottle recommends for the lowest temperatures you expect. Plain water, or a summer-strength mix, can freeze in the reservoir, the pipes or on the glass, just when you need it most.

The bottle's mixing chart is the authority, because concentrations differ between products. Some screenwash is sold ready-mixed; some needs diluting. Don't top up with washing-up liquid, which can leave smears and foam.

The MOT checks that the washers supply enough fluid to clear the screen alongside the wipers, so a frozen or empty system matters for the test as well as for the drive.

How do I stop my wipers freezing to the windscreen?

On a frosty morning, the rubber can freeze to the glass overnight. Before you start the car:

• Check whether the wiper switch is off. If you left it on, or your car has automatic rain-sensing wipers, they may try to move as soon as you turn the ignition on and tear the frozen rubber or strain the motor. Switch them off before you park when frost is forecast.
• Free the blades gently. Let the screen defrost first, then lift each blade carefully. Don't yank a blade that's stuck.
• Never use the wipers to clear ice. It wears the rubber and can damage the linkage. Clear the glass first, then use the wipers.

Some drivers lift the wipers off the glass overnight. On many cars the arms park under the edge of the bonnet, and lifting them there can chip the paint. Check the handbook: some cars have a service position that moves the arms up the screen first.

If the blades already streak or chatter, winter is a bad time to put off replacing them. Our guide to when to replace wiper blades lists the signs, and streaky or juddering wipers covers fixes in order.

How should I de-ice my windscreen?

• Start the engine and set the heater to the windscreen with the air conditioning on, which helps clear mist.
• Use a plastic scraper and a de-icer spray. Avoid anything metal, which can scratch the glass.
• Don't pour boiling water on the screen. The sudden temperature change risks cracking it, and the water can refreeze.
• Clear the whole screen, the side windows, the rear screen and the mirrors, not a porthole in front of the driver.
• Brush snow off the roof too, so it doesn't slide down over the windscreen when you brake.

Don't leave the car running unattended while it de-ices.

What does the Highway Code say about clearing windows?

Rule 229 of the Highway Code covers driving in adverse weather. It says that before you set off you must be able to see, so clear all snow and ice from all your windows, make sure your lights are clean and your number plates clearly visible and legible, and keep mirrors clear and windows demisted. The full wording is in the Highway Code on GOV.UK.

Rule 226 adds that you must use headlights when visibility is seriously reduced, generally when you can't see for more than 100 metres. You may use fog lights then, but must switch them off when visibility improves. Rule 236 warns not to use fog lights otherwise, because they dazzle other drivers and can hide your brake lights. Our rear fog light guide covers the bulbs and the rules.

Which car lights should I check before winter?

All of them, because the MOT checks headlamp aim and operation, sidelights, indicators and hazard lights, brake lights, the rear fog lamp (on cars first used from 1 April 1980), number plate lamps and rear reflectors. Driving with defective lights can also lead to a fixed penalty.

The brake lights and rear lamps are the hard ones to check alone. Our guide to checking your car lights on your own shows how to do it with a reflection or a phone video.

If a headlight bulb has failed, the one on the other side has done the same hours. Our guide on whether to replace headlight bulbs in pairs explains why many drivers change both. Of the 360 UK car generations where we've verified the dipped beam, 201 use an H7 bulb, 74 use an H4, 20 use an H11 and 43 have factory LED units that aren't replaceable as a bulb.

Check your car

Look up the exact bulbs and wiper sizes for your car before you need them, so you're not guessing in the dark. Our pages give every position checked against the handbook or two independent sources. Start at bulbs by car, wipers by car or choose your make. Popular winter lookups:

• Ford Fiesta Mk8 — H7 dipped, 28" driver blade
• Vauxhall Corsa E — H7 dipped, 26" driver blade
• Nissan Qashqai J11 — H11 dipped, 28" driver blade
• VW Golf Mk7 — H7 dipped, 26" driver blade

Common questions

Can I use plain water in my screenwash in winter?

It's best not to. Plain water can freeze in the reservoir, pipes or on the glass, and it does little to shift road grime. Use a winter screenwash mixed at the strength on the bottle.

Is it illegal to drive with ice on your windows?

Rule 229 of the Highway Code says you must be able to see, so clear all snow and ice from all your windows before setting off. Driving with a partly cleared screen means you can't see properly, whatever the weather.

Why do my headlights look dim in winter?

Road salt and grime build up on the lenses quickly in winter. Clean them before assuming a bulb has failed. If one side is clearly dimmer than the other after cleaning, the bulb may be near the end of its life.

Should I leave my wipers up overnight in frost?

Only if your car allows it without the arms hitting the bonnet. Check the handbook for a wiper service position, and make sure the wiper switch is off before you start the car on a frosty morning.

Checked against our verification rules. Spotted something wrong? Tell us.