Storing a collector car, and what sitting does to it

Most collector cars spend the overwhelming majority of their lives parked, which means storage is not a detail of ownership — it is the main thing you are doing with the car. Nearly every expensive problem that appears after a purchase was caused by how the car sat, not by how it was driven.

The good news is that doing this properly is cheap and mostly consists of not doing a few specific things.

What actually damages a parked car

Moisture, not cold. A cold dry garage is harmless. A sealed, humid space is where corrosion happens, and a car cover over a damp car makes it worse by holding the moisture against the paint. Ventilation beats insulation. A dehumidifier in a closed garage is worth more than a heater.

Ethanol in the fuel system. Pump fuel containing ethanol attracts water and degrades over months, and it is unkind to the rubber and cork in older fuel systems. Add a stabiliser rated for ethanol and fill the tank before storage: a full tank has less air in it, and less air means less condensation on the tank walls. Then run the engine long enough to carry stabilised fuel through the lines and into the carburettor or injectors, or the stabiliser is sitting in the tank protecting nothing.

Flat spots and sidewall damage. Tyres take a set under static load. Inflating above normal running pressure for storage helps, moving the car occasionally helps more, and getting the weight off the tyres entirely — ramps, cradles or stands — is best for long periods. Also note the date codes: tyres age out on a timetable of their own regardless of tread depth, and a twelve-year-old tyre with full tread is not a usable tyre.

A seized parking brake. Do not leave the parking brake engaged for long storage. Shoes bond to drums, cables seize. Chock the wheels instead, and leave a manual gearbox in gear if the car is on a level surface.

Rodents. They eat wiring insulation, they nest in air boxes and heater plenums, and the damage is both expensive and maddening to trace. Steel wool in the exhaust outlet, traps outside the car rather than inside it, and nothing edible anywhere nearby.

The battery. Use a proper maintainer that monitors and holds the charge, not an unregulated trickle charger that will cook the battery over a winter. Disconnecting instead is acceptable, but on anything with electronic memory it means losing settings and sometimes relearning.

Brake and clutch fluid. Glycol-based brake fluid absorbs water from the air continuously and that water corrodes cylinders and callipers from the inside. This is on a two-year clock regardless of mileage, and a car that sat for a decade without a fluid change has a brake system of unknown condition whatever the pedal feels like.

Before storing

• Wash and dry it thoroughly, including the underside. Road salt left on a car over a winter does more harm than the winter does.
• Wax or seal the paint, which is as much a moisture barrier as a cosmetic step.
• Change the oil if it is near due. Used oil holds combustion acids, and leaving them sitting against bearing surfaces for months is avoidable.
• Clean the interior completely — anything organic invites both mould and animals.
• Leave the windows very slightly open if the space is secure and dry, for air exchange.
• Use a breathable cover, or none. A plastic sheet is worse than nothing.

Bringing it back

Do not simply start it and drive. In order:

1. Look underneath for fresh fluid and for evidence of animals.
2. Check tyre pressures and look at the sidewalls for cracking.
3. Check every fluid level, and the brake fluid's condition rather than just its level.
4. Turn the engine over without starting it if it has been sitting for a long period — on many older engines you can do this by hand — to get oil moving before combustion loads the bearings.
5. Start it and let it reach temperature, watching oil pressure first and temperature second.
6. Test the brakes at walking pace before you need them. Surface rust on discs is normal; a pedal that goes soft or long is not.

What this means when you are buying

A car described as having been in long-term storage is not thereby preserved. It is a car with a known list of consequences, and the list is predictable: fuel system, brake hydraulics, all rubber, tyres, battery, and whatever the rodents found.

Price that work in. It is routinely a four-figure sum on an otherwise sound car, it is not optional, and it lands in the first month of ownership rather than someday. "Barn find" and "stored for twenty years" are descriptions of a maintenance backlog, not of condition.