Winter Storage Prep for a Collector Car

Clean going in, or it corrodes

The single most important storage decision is made before the car is parked: whether it is clean. A car put away with road film, salt residue from a late-season drive, bird droppings, or sap on the paint spends the whole winter with all of it in place, and none of it is inert.

Salt on steel in a cold, humid unheated garage corrodes faster than the same salt on a car that is being driven, because the driven car at least dries out. Droppings and sap keep etching and bonding. Road film holds moisture against the paint. By April the damage is done and it happened in the dark.

So the last thing before storage is a full decontamination — iron remover, clay, then protection — and a proper interior clean. Not a wash. A wash leaves the bonded contamination that does the damage.

What a Wisconsin garage does over five months

Humidity is the enemy. An unheated garage in winter goes through temperature swings that cause condensation on cold metal every time it warms, and that moisture sits on the underside, in the door seams and inside the cabin. Paint under a good sealant or coating sheds it; bare paint holds it.

Interiors suffer a different way. Leather dries out and stiffens over months with no use and no conditioning. Rubber seals dry and crack. Any organic material in the carpet — a crumb, a leaf, a spill — becomes a food source for whatever gets in. Clean going in, conditioned, and with nothing left behind to attract attention, an interior comes out of storage the way it went in.

A breathable cover keeps dust and drips off without trapping moisture. A plastic sheet traps moisture and is worse than nothing.

The things that are not detailing but matter

Fuel stabiliser and a full tank to reduce condensation in it. Tyres at higher pressure or the car on stands to avoid flat spots. A battery tender. Rodent deterrent, and the car checked monthly rather than in April. None of that is our job, all of it is worth doing, and the monthly check is the one people skip and regret.

Spring

A car that went in clean and protected comes out needing a rinse and an inspection, not a reset. Check the paint under the cover for anything that dripped through. Check the cabin for anything that moved in. Condition the leather. Then drive it.

If it went in dirty, spring is when the corrosion, the etching and the smell are discovered, and that is a considerably longer conversation. Our month-by-month guide puts storage prep in November for that reason.