The trouble is that automobiles, like everything else, are subject to the law of entropy. “Preservation” is about more than just keeping the odometer reading low. “Like-new” means something different after one, two, or three decades, even if the car still has plastic wrap on the steering wheel. The paint, upholstery, and trim may look flawless—but what about the bits you can’t see, like the complex systems and different materials that make up the driveline? Just because a car is like-new doesn’t mean it actually is new, or that you can just hop in and drive it home. We decided to call up some experts across the industry to answer a big question: What exactly is happening to a car when it sits?

First off, what’s happening to it while it sits depends on where it sits. Imagine a car in a museum—perhaps the Le Mans–winning Ford Mark IV at the Henry Ford Museum in Dearborn, Michigan. Now, think of that old pickup you once saw sitting in a field. Technically, they’re both decaying. One is just decaying far more slowly than the other. 

The race car lives in a perfectly curated world. The temperature in the museum is consistent and the humidity is just so: Low enough to deter moisture-loving insects and mold, high enough to prevent the tires and other rubber seals from drying out. A museum car’s tires may barely touch the ground, because the chassis sits on jack stands. The fluids in the car—fuel, coolant, oil—have either been drained or supplemented with stabilizing agents. The upholstery is regularly vacuumed to eliminate pests. Dust barely gathers on the body before someone gently sweeps it off.

The pickup, meanwhile, has been at the mercy of the weather for who knows how long. The tires have cracked and rotted. Salty air might be corroding metal. Insects and/or rodents might be living inside the cabin and engine bay. The engine’s cylinders may be dry, the gas in its rusty fuel tank a kind of goo, the oil gray instead of honey-colored. Its paint may be bubbling, its carpets mildewing. 

Those are two extreme examples, of course, but when it comes to the condition of a car, the storage (or display) environment makes all the difference, whether the car is Henry Ford’s original Quadricycle from 1896 or a brain scientist’s sporty Sentra from 1992. To keep a “like-new” car living up to its descriptor, the temperature must be consistent; otherwise, even the most immaculate car will bake, sweat, and/or freeze. The moisture in the air needs to be high enough to slow the decay of organic materials like tires but low enough to protect from rust. The room itself needs to be well-sealed to deter pests. The vehicle also needs a barrier (or two) between the paint and the dust, dirt, and grime that will accumulate. And that’s only the parts of the car you can see …

The Odometer Doesn’t Tell the Whole Story

No one is more familiar with finding automotive diamonds in rough storage situations than Tom Cotter, known as The Barn Find Hunter. When I called him to discuss this story, the consequences of bad storage were especially fresh on his mind: He had just bought a barn-find car (a 1986 Porsche 930 Turbo) with 16,000 miles. “That’s the good news,” he said. “The bad news is that it has not been driven since 1996, so nearly 30 years. And even though it had a plastic sheet on it, somehow it got filthy. Filthy. My heart breaks.” Even worse, the windows were open, and the car was infested with mice. It needs a thorough recommissioning: brakes, gas tank, fuel lines, fuel injection unit, fuel injector, fuel pump—and those are just the major areas, says Tom. He’s still in the process of figuring out how much the car needs, but if everything needs to be replaced, the work could cost as much as $40,000 usd/ $58,000 cad. Oh, and he’ll need a new set of tires—the car was parked on its original set from 1986. 

“Just because a car has low miles doesn’t mean it was well cared for,” says Cotter. “Cars go bad when they sit.” A perfect storage environment and a sedentary life don’t guarantee stasis, either: “There are things that happen inside the systems of a car that break down, like the rubber in a brake system or the rubber in our fuel system. It doesn’t matter if the car is hot or cold or clean or dirty, those things are going to break down.” One interesting system that is especially prone to degrading when a car sits is the exhaust, he says. “For every gallon (3.785 liters) of fuel that’s burned in a car, a gallon of water comes out the tailpipe. It’s just part of the combustion process. And so if you run the car and then turn it off and park it for 20 years, you’ve got at least a gallon of water (3.785 liters) sitting in the exhaust system—most of it, in the muffler. Unless it’s made of stainless steel or something, it’s going to just rot right out. There’s really nothing you can do about that.” 

The fluids and the metals in a car are often conspiring against each other. “One of the biggest challenges you have managing large collections—and with cars that sit, too—is coolant system corrosion,” says Scott George, curator of collections at the Revs Institute in Naples, Florida, who knows a thing or two about keeping old cars in peak health. “You’ve got brass, copper, aluminum, iron, steel, all coming in contact with water, and it can create a battery of sorts. It can almost create its own internal energy, which can attack certain metals that are most vulnerable,” like the vanes in a water pump, which are often made of a different metal than the pump itself. Using antifreeze doesn’t eliminate the problem: Those systems can corrode, too, damaging hose connections and water chambers in cylinder heads. “Corrosion in radiators, and things that attack solder and solder seams, are also a big challenge for anybody with large collections.”

Proper storage requires understanding of the car’s construction, because certain materials require special attention and/or precautions. Wool and horsehair, materials that are especially common in the upholstery of cars built before World War II, can attract cloth moths and carpet beetles. Cuong Nguyen, a senior conservator at The Henry Ford, who is heavily involved in the care of the museum’s 300-car collection, suggests vacuuming such cars each season. He also warns that some more modern wiring harnesses are made with soy-based materials that, while eco-friendly, attract mice. Sticky traps, he says, especially those without pheromones, can be good preventive measures for furry pests. 

Understanding how a car is built also helps set expectations for how it ages, even in the best conditions. For instance, different sorts of paints wear differently: Lacquer-based paint, used on most cars built before the late 1980s or early ‘90s, doesn’t hold up as well as the more modern, urethane-based version. Another notoriously finicky modern material covers the soft-touch buttons found in some Italian exotics from the 1990s or early 2000s. The black material gets sticky over time.

Best-Case Storage Scenario

Cotter, who owns a storage facility called Auto Barn in North Carolina, encourages enthusiasts to store their vehicles thoughtfully because they’re protecting their financial investment. “It might take you a half-day to get a car ready to lock up, but put a little bit of effort into it. You are maintaining your investment. It’s a mechanical portfolio. A car that’s parked haphazardly will more than likely go down in value.”

The best place to store a car—with any odometer reading—is in a clean, dry place with temperature and humidity control. To avoid flat spots on the tires, which can develop within a year, the car should be elevated, just slightly, on jack stands (as mentioned above, a trick used by museums) or lowered onto a set of tire cradles. If the fuel isn’t drained, it should be ethanol-free; the regular stuff turns into a gummy, gooey mess when it sits. If the fuel in the tank does contain ethanol, it should be supplemented with a fuel stabilizer. If the car was driven regularly before storage, the carpets in the driver’s side footwell should either be completely dry or propped up, away from the floorboards. Cotter explains why: moisture from the driver’s shoes may get onto and under the carpets, and it may mold the carpets or, worse, become trapped between the rubber backing and the sheet metal underneath, which may begin to rust.

Some sort of rodent protection, even a Bounce sheet, should be taken. (This nifty device, called Mouse Blocker, uses sonic pulses to keep the critters at bay.) One moisture-absorbing trick that Cotter recommends is cheap, and readily found at your local hardware store: charcoal, which absorbs moisture and odors. Ideally, the paint should be waxed and the car put under a cover. Feeling fancy? Look into a Car Capsule, the “bubbles” that the Detroit Historical Society uses to store its cars.

While in Storage

Of course, not all low-mile cars are barn finds like Tom’s Porsche. Many of them present amazingly well. Scott George weighs in. There’s an excitement, he says, about buying a car that appears locked in time and cosmetically perfect—free of nicks, scrapes, bumps, wrinkles. But some people, he says, may not think about what they’re getting into at a mechanical level: “Every time I see a later-model car sell with low mileage, what often goes through my mind is ‘cha-ching, cha-ching, cha-ching.’” He’s seen what can happen when cars sit for 25 or 30 years: “Everything functioning part of the automobile, maybe except for a total engine rebuild, has to be redone.”

Not all buyers may want to drive their pristine, low-mile prize, he admits—some may simply want to be the next owner, to park the car in their climate-controlled showroom as a trophy. There is nothing wrong with that, of course, but down the road, it may be a very costly one—if not for them, for the next person who buys it and wants to drive it. “Cars are operating machines,” George says. “They like to drive.”

At the very least, a car should be started once in a while, and run for more than 5 or 10 minutes—half an hour or so, at least, so that the engine and oil can come up to temperature and cooling fluids can fully circulate. Starting a car and quickly turning it off, says Cotter, “does more damage than if you just leave it alone because the cylinders are dry—there’s not enough oil in the system.”

Acids and moisture can build up, warns George, if a car doesn’t run long enough, “and exhaust systems can corrode from the inside out, and so forth.” He practices what he preaches: The Revs Institute has an unusually high commitment to keeping most of its 120-something collection running, and that means driving the cars—on a circuit loop, for the road cars, or on track, for the race cars, whether that’s at a historic racing event or during a test day where Revs rents out a facility.

Where a car is stored may make the most difference in preserving its condition, but how it is maintained during that period is a close second. “I have witnessed actually cars that 25 or 30 years old that literally sat,” says George, “and I’ve seen it firsthand: every functioning part of the automobile, maybe except for a total engine rebuild, has to be redone. The fuel systems, the fuel injectors, all of that stuff.” Maintaining a low-mile car in driving condition requires a balance of commitment and restraint: “There are some people that have just had these wonderful low-mileage cars,” says George, “and they have done annual maintenance and they have cared for the mechanical systems. They’ve just been cautious about how many mile miles they’ve put on.”

In short, the best way to keep a car in driving condition is to, well, drive it.

“Just because a car has low miles doesn’t mean it was well cared for,” says Cotter. “Cars go bad when they sit.” A perfect storage environment and a sedentary life don’t guarantee stasis, either: “There are things that happen inside the systems of a car that break down, like the rubber in a brake system or the rubber in our fuel system. It doesn’t matter if the car is hot or cold or clean or dirty, those things are going to break down.” One interesting system that is especially prone to degrading when a car sits is the exhaust, he says. “For every gallon of fuel that’s burned in a car, a gallon of water comes out the tailpipe. It’s just part of the combustion process. And so if you run the car and then turn it off and park it for 20 years, you’ve got at least a gallon of water sitting in the exhaust system—most of it, in the muffler. Unless it’s made of stainless steel or something, it’s going to just rot right out. There’s really nothing you can do about that.” 

The fluids and the metals in a car are often conspiring against each other. “One of the biggest challenges you have managing large collections—and with cars that sit, too—is coolant system corrosion,” says Scott George, curator of collections at the Revs Institute in Naples, Florida, who knows a thing or two about keeping old cars in peak health. “You’ve got brass, copper, aluminum, iron, steel, all coming in contact with water, and it can create a battery of sorts. It can almost create its own internal energy, which can attack certain metals that are most vulnerable,” like the vanes in a water pump, which are often made of a different metal than the pump itself. Using antifreeze doesn’t eliminate the problem: Those systems can corrode, too, damaging hose connections and water chambers in cylinder heads. “Corrosion in radiators, and things that attack solder and solder seams, are also a big challenge for anybody with large collections.”

Proper storage requires understanding of the car’s construction, because certain materials require special attention and/or precautions. Wool and horsehair, materials that are especially common in the upholstery of cars built before World War II, can attract cloth moths and carpet beetles. Cuong Nguyen, a senior conservator at The Henry Ford, who is heavily involved in the care of the museum’s 300-car collection, suggests vacuuming such cars each season. He also warns that some more modern wiring harnesses are made with soy-based materials that, while eco-friendly, attract mice. Sticky traps, he says, especially those without pheromones, can be good preventive measures for furry pests. 

Understanding how a car is built also helps set expectations for how it ages, even in the best conditions. For instance, different sorts of paints wear differently: Lacquer-based paint, used on most cars built before the late 1980s or early ‘90s, doesn’t hold up as well as the more modern, urethane-based version. Another notoriously finicky modern material covers the soft-touch buttons found in some Italian exotics from the 1990s or early 2000s. The black material gets sticky over time.

Best-Case Storage Scenario

Cotter, who owns a storage facility called Auto Barn in North Carolina, encourages enthusiasts to store their vehicles thoughtfully because they’re protecting their financial investment. “It might take you a half-day to get a car ready to lock up, but put a little bit of effort into it. You are maintaining your investment. It’s a mechanical portfolio. A car that’s parked haphazardly will more than likely go down in value.”

The best place to store a car—with any odometer reading—is in a clean, dry place with temperature and humidity control. To avoid flat spots on the tires, which can develop within a year, the car should be elevated, just slightly, on jack stands (as mentioned above, a trick used by museums) or lowered onto a set of tire cradles. If the fuel isn’t drained, it should be ethanol-free; the regular stuff turns into a gummy, gooey mess when it sits. If the fuel in the tank does contain ethanol, it should be supplemented with a fuel stabilizer. If the car was driven regularly before storage, the carpets in the driver’s side footwell should either be completely dry or propped up, away from the floorboards. Cotter explains why: moisture from the driver’s shoes may get onto and under the carpets, and it may mold the carpets or, worse, become trapped between the rubber backing and the sheet metal underneath, which may begin to rust.

Some sort of rodent protection, even a Bounce sheet, should be taken. (This nifty device, called Mouse Blocker, uses sonic pulses to keep the critters at bay.) One moisture-absorbing trick that Cotter recommends is cheap, and readily found at your local hardware store: charcoal, which absorbs moisture and odors. Ideally, the paint should be waxed and the car put under a cover. Feeling fancy? Look into a Car Capsule, the “bubbles” that the Detroit Historical Society uses to store its cars.

While in Storage

Of course, not all low-mile cars are barn finds like Tom’s Porsche. Many of them present amazingly well. Scott George weighs in. There’s an excitement, he says, about buying a car that appears locked in time and cosmetically perfect—free of nicks, scrapes, bumps, wrinkles. But some people, he says, may not think about what they’re getting into at a mechanical level: “Every time I see a later-model car sell with low mileage, what often goes through my mind is ‘cha-ching, cha-ching, cha-ching.’” He’s seen what can happen when cars sit for 25 or 30 years: “Everything functioning part of the automobile, maybe except for a total engine rebuild, has to be redone.”

Not all buyers may want to drive their pristine, low-mile prize, he admits—some may simply want to be the next owner, to park the car in their climate-controlled showroom as a trophy. There is nothing wrong with that, of course, but down the road, it may be a very costly one—if not for them, for the next person who buys it and wants to drive it. “Cars are operating machines,” George says. “They like to drive.”

At the very least, a car should be started once in a while, and run for more than 5 or 10 minutes—half an hour or so, at least, so that the engine and oil can come up to temperature and cooling fluids can fully circulate. Starting a car and quickly turning it off, says Cotter, “does more damage than if you just leave it alone because the cylinders are dry—there’s not enough oil in the system.”

Acids and moisture can build up, warns George, if a car doesn’t run long enough, “and exhaust systems can corrode from the inside out, and so forth.” He practices what he preaches: The Revs Institute has an unusually high commitment to keeping most of its 120-something collection running, and that means driving the cars—on a 40-, 50-, or 60-mile (approx. 64-, 70-, 97 kilometer) loop, for the road cars, or on track, for the race cars, whether that’s at a historic racing event or during a test day where Revs rents out a facility.

Where a car is stored may make the most difference in preserving its condition, but how it is maintained during that period is a close second. “I have witnessed actually cars that 25 or 30 years old that literally sat,” says George, “and I’ve seen it firsthand: every functioning part of the automobile, maybe except for a total engine rebuild, has to be redone. The fuel systems, the fuel injectors, all of that stuff.” Maintaining a low-mile car in driving condition requires a balance of commitment and restraint: “There are some people that have just had these wonderful low-mileage cars,” says George, “and they have done annual maintenance and they have cared for the mechanical systems. They’ve just been cautious about how many mile miles they’ve put on.”

In short, the best way to keep a car in driving condition is to, well, drive it. For the Silo, Grace Houghton.