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Why a Seasonal Routine Pays Off

Cars rarely fail at a convenient moment. The battery that has been quietly weakening since September tends to give up on the first frosty morning you actually need to be somewhere, and the air conditioning that has not been touched for two years usually reveals itself on the hottest day of July. A short, structured check before winter and before summer takes perhaps an hour and costs very little, yet it removes most of the surprise from running a car. It also keeps costs predictable: a battery replaced on your terms is a far better outcome than a recovery call-out and a replacement fitted at short notice.

Whether you drive a tidy independent-dealer purchase or a car you have run for years, the same four areas repay attention twice a year: battery, coolant, air conditioning and tyres.

Battery Health: The Most Common Winter Failure

Cold weather thickens engine oil and slows the chemical reaction inside a lead-acid battery, so a battery at 70 per cent health in June can behave like a flat one in January. Check it before the first cold snap, not after.

• Resting voltage: with the engine off and the car rested for an hour, a healthy battery should read around 12.6 volts. A reading of 12.4 volts suggests roughly half charge; 12.0 volts means it needs charging and probably testing.
• Charging voltage: with the engine running, expect 13.8 to 14.4 volts across the terminals. Lower than that points to a tired alternator or a slipping belt.
• Physical condition: look for bulging cases, crusty white deposits around the terminals and any sign of dampness. Clean terminals cost pennies and prevent a lot of grief.
• Age: most batteries last four to six years. Beyond five years, budget for replacement rather than waiting for a failure.

Short journeys are the quiet killer. If your routine is a two-mile school run, the battery never fully recharges. A fortnightly longer run, or a smart charger in the garage, makes a real difference.

Coolant Strength and the Cooling System

Coolant does two jobs, and both matter seasonally. In winter it must not freeze — a frozen block can crack an engine — and in summer it must carry heat away without boiling. The antifreeze concentration also protects against corrosion inside the radiator, heater matrix and water pump.

A 50:50 mix of antifreeze and water typically protects down to around minus 37°C, and a garage can check the strength in seconds with a refractometer or hydrometer. If the reading suggests protection only to minus 10°C, a top-up or a full change is sensible.

• Check the level only when the engine is cold — never open a hot expansion tank.
• Top up with the correct specification of antifreeze, not plain water, which dilutes protection.
• Look out for a dropping level with no visible leak; that can indicate a head gasket issue worth investigating early.
• Most manufacturers recommend a coolant change every five years or so, or at a stated mileage.

Air Conditioning: Worth Using All Year

Air conditioning is often thought of as a summer-only system, but it is one of the best demisting tools you have. Running it in winter removes moisture from the cabin air and clears a misted windscreen far faster than heat alone.

That is exactly why it should be checked before the cold arrives as well as before the heat. A system that has lost refrigerant will still blow air, just not cold air, and the compressor needs occasional use to keep its seals lubricated. Run the air conditioning for ten minutes every couple of weeks, including through winter.

• Cooling performance: if the vents take several minutes to feel properly cold, the system likely needs regassing.
• Smells: a musty odour usually means bacteria in the evaporator. A cabin filter change and a clean often solve it.
• Regassing: many cars benefit from a check every two years; leaks should be found rather than simply topped up.

Tyres: Tread, Pressure and Temperature

Tyres are your only contact with the road, and their behaviour changes markedly with the seasons. As a rule of thumb, tyre pressures fall by around one psi for every 5 to 6°C drop in ambient temperature, so pressures set in a warm September can be noticeably low by December.

• Tread depth: the legal minimum is 1.6mm, but wet and winter grip falls away well before that. Three millimetres is a sensible point at which to plan replacement.
• Pressures: check monthly and before long journeys, using the figures on the door pillar or fuel flap rather than the maximum on the sidewall.
• Condition: examine sidewalls for cuts and bulges, and look for uneven wear that points to alignment or suspension problems.
• Seasonal tyres: below about 7°C, summer rubber hardens. If you regularly drive rural roads in winter, a set of winter or all-season tyres transforms cold-weather grip.

Do not forget the spare or the tyre sealant kit, and check that the jack and wheel brace are present and usable.

Building a Simple Seasonal Schedule

A workable routine is easier than it sounds, and it fits neatly around an annual service.

• October: battery test, coolant strength, tyre pressures and tread, wipers and screenwash topped up to a winter concentration, plus a check of all lights.
• March or April: air conditioning performance, coolant level, tyre condition, brakes and a thorough clean underneath to remove road salt.
• Monthly, all year: tyre pressures, screenwash, oil level and a quick walk around the car for bulbs, chips and leaks.

None of this replaces a proper service, but it does mean you arrive at one with fewer nasty surprises. Cars respond well to being looked after, and a little seasonal attention keeps a used car feeling dependable for far longer than most owners expect. If in doubt about any of these checks, a trusted local workshop can carry them out quickly and explain what they find in plain terms.