A stored car does not age evenly. Each part runs on its own clock. The battery goes first, in weeks. Tyres follow at about a month. Damp works over months, and brake fluid and oil age by the calendar whatever the mileage. Plan the storage around those clocks and the car comes back ready to drive.
A healthy modern car can usually sit for about two weeks with no attention. After that, problems arrive in a fairly fixed order: the 12 volt battery first, then the tyres at about a month, then damp, fuel and fluids over the following months. How long a car can sit depends on which of those you have dealt with.
Very little. Most modern cars with a fairly healthy battery should last at least two weeks without being started, according to the AA. Brake discs may show a light film of surface rust, which the RAC notes can form after a single damp night and clears after a few normal stops. Park it somewhere dry and leave it alone.
Yes, with a battery conditioner. A modern car draws current while locked, for the alarm and keyless entry, so the 12 volt battery runs down from the day it stops. VARTA puts a full battery at 12.8 volts and says to recharge below 12.4. CTEK says sulphation can start below 12.4 volts, and that capacity does not come back. A smart conditioner holds the battery full for as long as the car stands.
A month is also the line for tyres. Continental says flat spots from a few days or weeks go once the tyres warm up, but after a month or longer under load they can become semi-permanent, and normal driving will not remove them. Continental suggests about 3 PSI extra before a long stand, within the car maker's limits; tyre makers differ on pressure, as our supercar storage guide explains. Our own advice is to roll the car a short distance by hand every few weeks, so a different part of each tyre carries the load, or to put it on stands.
Yes, if the battery is on a conditioner, the tyres are protected and the air is dry. Damp is now the risk to watch. The Canadian Conservation Institute gives mould about 100 days to germinate at 70% relative humidity on leather and other protein-rich surfaces, 10 days at 80% and 2 days at 90% or more. Any spell below 55%, it says, stops the growth, which is why a building held under 55% matters so much.
Brakes can also stick. The AA warns that brakes can seize when a car stands for a long time with the parking brake on, and says to leave it off only on private land with the wheels securely chocked. So chock the wheels, leave the car in gear or Park, and leave the handbrake off. Some electric parking brakes apply themselves at switch-off, so check the handbook.
Yes. Six months is about a full winter lay-up, late October to early April, and fuel and oil join the list. The Federation of British Historic Vehicle Clubs recommends ethanol-free petrol in place of E10 for an extended lay-up, and warns against leaving the fuel system dry, because gaskets and elastomers shrink and crack. For a modern car, super unleaded is E5, with up to 5% ethanol against up to 10% in E10. Leave the tank nearly full, which leaves less air for moisture to condense in.
Oil ages too. Castrol advises changing it at least once a year whatever the mileage, because it breaks down whether the engine runs or not. If it is close to due, change it before the car goes away. Our winter storage guide covers the rest.
Yes, but some jobs fall due on dates. Brake fluid absorbs water from the air. ATE and Bosch give standard DOT 4 fluid up to two years, and ATE says cars built before 1990 should have it changed yearly. Check it before the car is driven hard; our track car storage guide shows how far water lowers the boiling point.
Tyres age by date as well. Michelin recommends a yearly professional inspection once tyres have been in use for five years, and replacement ten years after manufacture, regardless of tread. The four-digit date code on the sidewall gives the week and year of manufacture.
Only if it gets properly warm. The AA suggests starting a car once a week and running it for about 15 minutes. The RAC suggests driving for more than 20 minutes every few weeks. The AA says this recharges the battery and helps keep the engine in good condition. The catch is in the chemistry of burning petrol.
Burning petrol makes water. Taking octane as a stand-in for petrol, each kilogram burnt produces about 1.4 kilograms of water vapour, so a litre of petrol burnt makes roughly a litre of water. The US government's fuel economy guide puts idling at a quarter to half a US gallon an hour, about 1 to 2 litres. Fifteen minutes on the drive therefore makes roughly a quarter to half a litre of water. Most leaves as steam. Some condenses in a cold exhaust, and Castrol notes that when an engine never fully warms up, moisture stays in the oil.
A run that reaches full working temperature drives that moisture off. A short idle on a cold morning leaves some of it behind, in the exhaust and in the oil. So a battery conditioner is the better way to keep the battery charged, and the engine either stays still or gets a proper drive.
If you stop taxing and insuring a car, you must declare it off the road with a SORN, which means keeping it in a garage, on a drive or on private land. You get a refund for any full months of tax left, and GOV.UK says a SORN does not need renewing.
A taxed car must be insured. A SORN car may go on a public road only to or from a pre-booked MOT or other test. A car whose MOT has run out may only be driven to a pre-arranged MOT or to somewhere it will be repaired. GOV.UK sets no national time limit on leaving a taxed, insured car parked on a street. Councils decide whether a car is abandoned; Elmbridge Borough Council, for example, lists flat tyres among the signs it looks for. Our insurance post covers laid-up cover.
Look underneath for leaks, check the tyres' pressure and date code, and test the battery before the first start. Expect some vibration for the first few miles if the tyres have flat spots; temporary ones go as the tyres warm up. If the car stood for a year or more, check the brake fluid's date before you drive it hard.
Yes. A SORN car does not need cover to drive, but a laid-up policy can still cover it against fire and theft while it is stored. Our insurance post explains who covers a stored car.
Only if it stays dry, with humidity under 55%. A heater on its own can make things worse: warm air holds more moisture, and it condenses on cold metal as the garage cools overnight. A dehumidifier does more good. Our convertible storage guide explains why a damp cabin stays damp even inside a dry building.
Henry's Car Barn has stored cars since 1984, from sites in Warwickshire, London, Hampshire and West Sussex, plus a fifth at Thruxton from November 2026. Every car is inspected on arrival, air dried for 24 hours and photographed, then put away with the handbrake off, under a breathable cover, on a battery conditioner. The sites are inspected daily and the conditioners are checked weekly. We collect from your door with our own transporter, and can move cars across the UK and Europe.
