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Published Jan 2025
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20 April, 2020
Your car performs best when it's used regularly, especially when it's given a long, continuous run.
Along with your battery, there are other components to keep an eye on if your car is sitting unused for long periods.
If you’re not using your car very often or not at all for longer periods of time, a little bit of preventative maintenance can help keep it in shape while it’s sitting unused.
If possible, take it for a drive once a week for about 30 minutes to warm up the engine and circulate your car’s fluids. Just starting it and letting it idle is not the best way to achieve this. An important thing to note, however, is that while a short drive is enough to warm the engine and circulate fluids, it's not enough to charge the battery.
But if that’s all that you can manage at any one time, at least press the brake pedal and give the steering wheel a twist in each direction while it’s idling as well.
Sitting idle for two to four weeks
If you won’t be using it at all for two or more weeks, here are some things to keep in mind.
Keeping your car under cover and protected from the elements is important, especially in winter.
Try not to park on grass or lawn for long periods. This can help prevent moisture getting where it shouldn’t and keep your lawn healthy too. Ideally your car should be kept in an enclosed or covered carport with good ventilation.
If your car will be sitting idle for up to four weeks, make sure it’s parked on a flat surface with suitable wheel chocks under all four tyres. Once it’s secured with wheel chocks, release the handbrake. This is to prevent the brake friction material from fusing to the rotor (or drum) after a sustained contact period. If it has an automatic transmission, put it in Park, and for a manual transmission vehicle, leave it in gear.
Letting tyres go flat can damage them. Try to keep the tyres inflated to the correct pressures while the car is parked.
For periods longer than four weeks
For periods longer than four weeks, if you have the right gear, consider raising the car so the tyres are not touching the ground. Use axle stands for support. The weight of the vehicle resting on the tyres in the same position for a prolonged period can damage the tyres at the point where they’re resting on the ground.
Petrol does have a shelf life so if you won’t be using your car for more than a month, leave a minimal level of petrol in the tank so when you do fill up, the older fuel will be diluted with fresh fuel. For diesel vehicles do the opposite. Fill the tank to prevent moisture forming inside the tank which can cause problems.
Your car’s battery is probably the one component which may suffer most from lack of use.
If your car will be unused for less than two weeks, we don’t recommend disconnecting the battery in a modern vehicle. Depending on the make, model and age, disconnecting the battery may result in losing some of your vehicle’s computer settings.
If it’s going to be more than two weeks, ensure the battery is fully charged and if it has removable caps, check that the electrolyte level is correct. If in doubt, contact RAC or an automotive workshop for advice.
Hooking up a battery charger
If you’re going to be using a battery charger, the best type is a smart charger which detects how much charge is needed and stops when the battery has reached capacity.
Before you start charging, make sure you have plenty of ventilation and no open flames around you. Battery gases are highly flammable and toxic. Follow the charging instructions on the battery. Before you start, check the battery case for cracks. Don’t charge it if you find damage.
Always connect the charger to the battery before switching the charger on. And before you disconnect it from the battery, switch the charger off.
If you find your battery keeps losing its spark even with regular charging, and assuming there’s nothing else wrong with the vehicle, it’s probably time to replace the battery.
Batteries are more likely to fail when they’re either very hot or very cold so winter can take its toll on a battery that’s already close to the end of its serviceable life.
Warning signs that your battery might be about to fail include a grinding or clicking sound when you engage the ignition, the car cranking slowly when you start it and the headlights appearing dim when idling but brightening when the engine is revved.
Finally, if your car will be sitting unused for any period of time, give it a good clean, not just outside but inside as well, especially if you’ve had kids going in and out of it. And keep an extra eye out for any food scraps that may be left behind to avoid any nasty odours when you get back inside.
Need mechanical advice?
RAC members can call our free motoring advice helpline from Monday to Friday, 9am to 5pm.
