Winter Car Checks: What to Look at Before the First Frost

Every year it’s the same. The first proper frost hits Sheffield and the phone starts ringing with cars that won’t start, tyres that won’t grip and screens nobody can see out of. Hardly any of it is bad luck. It’s the same handful of things every time, and most of them take five minutes to check.

Here’s what we look at on our own cars before winter, and what you can check on your drive this weekend.

Start with the battery

If you only check one thing, make it this. Older cars used to warn you. They’d turn over a bit slower each morning for a week or two and you’d know the battery was on its way out. Modern cars don’t do that. Stop-start, heated screens and seats and all the electrics mean the battery is worked hard on every journey. When it goes, it tends to go all at once, usually on the coldest morning of the year.

The cold hits it from both sides. A battery puts out less power when it’s cold, and a cold engine needs more power to start. A battery that just about copes in October can leave you stuck in December.

Short trips make it worse. Lots of five-minute runs take more out than the alternator puts back, which is why we see town cars lose batteries early.

The only way to know where yours is at is to test it properly, checking its actual condition rather than just the voltage. We do that for free, and there’s more on that below.

Tyres: tread and pressures

The legal minimum is 1.6mm across the middle three-quarters of the tyre, all the way round. That’s the law, not a safe number. Below 3mm a tyre’s grip in the wet drops off and stopping distances get longer, which is why we recommend changing at 3mm. On a cold, wet Sheffield hill, that’s the difference you’ll feel.

The quick check is a 20p coin. Push it into the main grooves, and if you can see the outer band of the coin, you’re close to the legal limit and need it looked at now. The coin won’t tell you whether you’re at 3mm, though. A cheap tread depth gauge will, or we can measure it for you.

Pressures matter more in winter than people think. Tyres lose pressure as the temperature drops, so one that was right in September can be soft by November. Check them cold, before you’ve driven anywhere. The right figures are in your handbook or on the sticker inside the driver’s door or fuel flap.

While you’re down there, look for cracks, bulges or anything stuck in the tread. A bulge in the sidewall means the tyre needs replacing, not watching.

Seeing and being seen

Short days mean more driving in the dark, so walk round the car with the lights on: dipped beam, main beam, sidelights, indicators, fog lights, reverse light and the number plate light. For the brake lights, get someone to stand behind, or reverse up to a garage door or window at night and check the reflection.

Wipers should clear the screen in one sweep. If they smear, judder or leave streaks, the rubber’s done. Lift them off the glass and run a finger along the edge, because splits are easy to feel.

Fill the washer bottle with proper screenwash, not just water. Water freezes in the bottle and the pipes, and then you can’t clear salt spray off the screen on a gritted road, which is exactly when you need it.

On frosty mornings, clear the whole screen and every window, not a letterbox in the middle. The Highway Code says you must be able to see out of all your windows, and that your lights and number plates must be clear too. Don’t pour boiling water on the glass, and don’t leave the car running unattended while it defrosts. Cars get taken off driveways that way, and your insurer may not pay out if yours is.

Coolant and antifreeze

Coolant does two jobs. It stops the engine overheating, and the antifreeze in it stops the water in the system freezing. If it’s weak, a hard frost can freeze it, and frozen coolant expands. At best that’s a split hose. At worst it’s a cracked block or a damaged head, which is an expensive way to find out in January.

With the engine cold, check the level in the expansion tank is between the min and max marks. Never open it when it’s hot. If it needs topping up, use the type your handbook specifies, because mixing different coolants can do more harm than good. If the level keeps dropping, there’s a leak somewhere and it needs looking at.

The level only tells you there’s enough. It doesn’t tell you it’s strong enough, and that needs a tester. It’s part of our free check. While the bonnet’s up, check the oil too.

What to keep in the boot

You don’t need a survival kit, just a few things that make a breakdown a lot less miserable:

• Ice scraper and de-icer
• A torch (your phone’s works until the battery dies)
• Warm coat, gloves and a blanket
• A charged power bank and cable
• Jump leads or a jump pack
• A spare bottle of screenwash
• Water and a snack if you’re going any distance
• A small shovel if you live up one of Sheffield’s steeper hills

How we do it at GT

If you’d rather we did all this, book the car in for our free winter health check. We test the battery properly, check the tread and condition of all four tyres, every bulb front and back, the wipers and washers, and the coolant, brake fluid and oil.

If everything’s fine, we tell you and you’re on your way. If something needs doing, we show you what we found and give you the price before we touch it. Small jobs like a bulb or a screenwash top-up (£12) can usually be done while you’re here.

The check is free, but please book in first so we can fit you in. If the car’s due a service or MOT anyway, have it done at the same time.

See our free winter health check →