How to Store a Car Long Term Without Coming Back to Problems

Storing a vehicle is where good intentions meet a chemistry that keeps moving while you are not watching. A battery discharges, oil oxidises, fuel condenses, seals perish, tyres deform, and insects build nests. None of it happens dramatically, and most of it is preventable, but the ones that are not prevented are discovered at exactly the moment you expect the car to be ready.

This guide covers what actually degrades during storage and how to prevent each one.

Decide Honestly Whether to Store It

The best way to avoid storage problems is not to store the vehicle. If the reason for storing it is financial, an assessment of what it costs to keep versus what it costs to move or to sell is worth doing honestly, because storage fees, insurance, and the accumulated risk usually exceed the cost of selling it. Where a vehicle has a genuine reason to be stored, such as a classic, a project, or a vehicle used seasonally, the advice below applies.

Where a vehicle will stand for a few months, the biggest risk by a wide margin is the battery. Where it will stand for a year or more, add the fuel system and the rubber.

The Battery

A battery in a stored vehicle is the single most common reason a car will not start when you return, and it is entirely preventable.

A vehicle in storage draws a small current continuously, from the alarm, the immobiliser, the clock, the body control module, and any aftermarket device. Depending on the vehicle, that is enough to flatten a battery in a few weeks and a smaller battery in a few days.

The correct solution is a maintenance charger, which holds the battery at full charge and switches off when it is full rather than overcharging it. A trickle charger that is not designed for long-term storage will cook the battery. Connecting the charger before the vehicle is left, rather than after a week of standing, is the important part. The causes and the measurement are in how to stop a car battery from dying, and the heat damage angle is in why a battery dies in hot weather.

Cover It, but Ventilate It

A breathable car cover is worth more than a waterproof one over a long storage, because a sealed cover traps condensation inside it and creates a damp environment against the paint, which is exactly the condition you are trying to avoid. A cover that also blocks ventilation encourages rust in the arches and under the sills. Where the vehicle is stored indoors in a dry, ventilated space, no cover is needed at all.

Where the vehicle is outside, park it in the open rather than under a tree, because a tree drips, birds perch, and leaves and sap accumulate. Keep it away from a wall if there is a choice, because that reduces airflow and creates a damp pocket on one side. Avoid a concrete surface if it can be avoided, because it wicks moisture and can cause damp rising into the underside.

Tyres

Tyres deform under a static load, and the deformation causes flat-spotting on the section that was in contact with the ground. If the storage lasts long enough, the sidewall can take a permanent set, which produces a vibration at speed and can damage the tyre. Inflate to the maximum of the placard's range before storing, because the higher pressure resists the deformation.

Where the vehicle will stand for months, either move it periodically or use axle jacks or wheel chocks to take the weight off the tyres. Driving the vehicle a few hundred metres every few weeks moves the flat spot, exercises the brakes and the steering, and circulates the fluids, which is worth more than anything else in this list.

The Fuel System

This is where a great deal of the damage done to a stored vehicle happens, and it is the one that is most often overlooked.

Fuel absorbs moisture from the air, particularly ethanol-containing fuel, and that moisture condenses in the tank and in the fuel lines. It also degrades, particularly a diesel where diesel fuel goes off badly with age, producing a layer of water and a varnish-like deposit that can block the injectors and the pump. A diesel that has been stored with old fuel and then run will frequently need its entire fuel system cleaned, and in the worst case its pump replaced.

For a petrol engine, filling the tank with fresh fuel before storing is the right move, because a full tank has less air volume and therefore less condensation. For a diesel, the advice is the opposite: run the fuel down as far as it is practical without emptying it, because diesel degrades faster and absorbs water faster. Where storage exceeds a few months, a fuel stabiliser is worth adding, and it must be added before storage rather than after.

Where the vehicle has a fuel injection system with a high-pressure pump, running the engine until the tank is properly empty before storage reduces the risk of the pump and injectors corroding from standing fuel.

The Oil

Oil in a stored engine does not degrade dramatically, but it does absorb moisture and it sits against metal surfaces that can corrode, particularly where the vehicle stands outside in a humid climate. For a storage of a few months, the existing oil is fine and should not be changed on the day it is put away, because an oil change immediately before storage leaves fresh oil that has to be run in.

Where the storage is longer than six months, an oil change before storing is worthwhile, using the correct specification. Where an engine has been used very little and is known to have condensation in it, running it until full temperature regularly during storage is the better answer. The specification reasoning is in our guide to changing engine oil.

Seals and Rubber

Rubber perishes with age and with exposure, and a vehicle that stands for a year will develop hardened window seals, perished door seals, and brittle wiper blades. The seals matter because water enters through them, and water that cannot evaporate is what causes the rust that then does real damage.

Opening and closing the doors periodically moves the seals and helps them retain their shape. Wiper blades that have been stretched or that have become brittle should be replaced before the vehicle is used again, because a blade that snaps on first use is a common and easily avoided problem. The wiper fault that develops without use is covered in five reasons a car wiper runs continuously.

Pests and Animals

Rodents and insects nest under the bonnet, in the air intake, and around the wiring, and the damage they cause is genuinely expensive: chewed loom, blocked fuel lines, and a chewed airbox. It happens quickly and it happens without warning.

Before starting a stored vehicle, look under the bonnet with a torch, look inside the air intake ducting, and check around the exhaust and the front bumper. Check the air filter and the cabin filter for nesting material. This check takes five minutes and it can prevent a very expensive repair. Keeping the vehicle moving is the only reliable deterrent, and where that is impossible, some owners use rodent deterrent devices in the engine bay.

Brakes, Rotors, and Drivetrain

A vehicle that stands still for a year will have surface rust on the brake discs, which produces a noise on the first drive and a reduced braking performance until the surface has been used off. It is not dangerous but it is alarming. Driving the vehicle a few miles at moderate speed on a dry road clears it.

With the vehicle on a lift, or even on the ground with the handbrake released and the gear engaged, taking up the slack on the caliper pistons prevents them from corroding in one position. Where the handbrake is left applied, the pads can corrode onto the discs and the caliper can seize, which is a genuine failure to correct before driving. Releasing the handbrake before storage is a small step that avoids a real problem.

Before Starting It Again

Do not simply start it. Check the oil level first, and be aware that a stored vehicle may have a low oil level because the oil has settled or because a small leak has developed. Check the coolant level cold. Check the brake fluid, which is hygroscopic and deteriorates with time in any vehicle, and where storage has been long, plan on replacing it. Turn the key and run it without driving for several minutes and listen. Then drive it gently for fifteen to twenty minutes, which circulates the fluids, clears surface rust from the brakes and the exhaust, and re-lubricates components that have been static.

Expect a period where the vehicle runs differently. The air filter may have accumulated debris, the fuel system may have water in it, the battery may be weak, and the tyres may be out of shape. Several of these are covered in how to test a used car, which is the same set of checks that apply to a vehicle you have not driven for months.

The Practical Checklist

Fit a maintenance charger before you leave it. Inflate the tyres to the maximum. Fill with fresh petrol or run the diesel as low as practical. Add a fuel stabiliser if storage exceeds three months. Release the parking brake. Wash and clean the vehicle, because dirt and road salt hold moisture against the paint. Check under the bonnet for nests before the first start. Then move the vehicle periodically if at all possible, because a few kilometres every few weeks prevents nearly everything on this list.

If this guide was helpful, you may also want to read why a car battery dies in hot weather for the storage-related damage, how to check a used car before you buy it for the post-storage checks, and how to remove rust from a car for the corrosion that a damp stored vehicle will otherwise develop.