Many car owners face the prospect of not driving their vehicle for an extended period of time. Perhaps you need to leave your car unused while traveling long-term, or maybe you want to store your classic car over the winter. Regardless of the reason, a common question arises: can you let a car sit unused for 6 months or longer?
Quick Answer
Yes, you can generally let a car sit unused for up to 6 months as long as you take proper precautions. The most important steps are fuel stabilization, battery maintenance, preventing rodent infestation, putting the vehicle on jack stands, and planning ahead of time. With proper preparation and maintenance, cars can sit much longer without regular use.
Effects of Letting a Car Sit
Letting a car sit idle for an extended time can lead to some detrimental effects if precautions are not taken:
- Dead battery – Lack of regular engine starts allows the battery to drain over time.
- Flat spots on tires – Long periods of remaining stationary in one position can cause flat spots on the tire tread.
- Fuel degradation – Gasoline and diesel can start to deteriorate in as little as 30 days.
- Rodent damage – Mice and other rodents may nest in the engine or chew through wires.
- Corrosion – Lack of movement can lead to corrosion build up in various components.
- Dried seals – Rubber seals around doors and windows can dry out and crack.
However, with some preparation and periodic maintenance, these detrimental effects can be minimized or prevented while your car sits.
Steps to Prepare Your Car for Long-Term Storage
If you plan on letting your car sit for 6 months or longer, here are some important steps to take beforehand:
1. Stabilize the Fuel
One of the most critical steps is to add fuel stabilizer to the gas tank. Fuel stabilizers contain antioxidants and other compounds that help prevent gasoline from oxidizing and going bad while sitting over time. Without fuel stabilization, gas can start to degrade in as little as 30 days.
Add fuel stabilizer to a full tank of fresh gas. Drive the car afterward to circulate the stabilized fuel through the fuel system. The recommended concentration is typically around 3000 PPM or 3000mg per gallon of gas. Be sure to use a reputable brand of fuel stabilizer and follow the directions.
2. Disconnect the Battery
Even very healthy car batteries will slowly self-discharge when the car sits unused for weeks or months. And the various electronic modules in the car still draw some power even when shut off. To prevent the battery from draining to the point where the car may no longer start, disconnect the negative battery cable.
An even better option is to remove the battery from the vehicle and store it on a trickle charger. This will maintain the battery charge while minimizing sulfation of the lead plates. Periodically crank the engine over by hand to circulate oil while the battery is out.
3. Change the Engine Oil and Filter
Used motor oil contains contaminants from combustion and can start to oxidize or gel over time, especially at higher ambient temperatures. Perform an oil change ahead of storage using quality synthetic or conventional oil.
You can also add antioxidants to the fresh oil to further help prevent oxidation. Make sure to replace the oil filter as well.
4. Prevent Rodent Infestation
Mice, rats, squirrels and other rodents are attracted to the warm, dry shelter of parked cars. They can chew through brake lines, electrical harnesses, upholstery and insulation over periods of neglect. Here are some tips to deter them:
- Seal any openings with wire mesh, foam or metal plates.
- Clean the vehicle interior to remove traces of food.
- Place traps around the exterior and check/reset them periodically.
- Use moth balls or cotton balls soaked in peppermint oil as a deterrent.
- Park over pavement if possible rather than vegetation.
5. Inflate the Tires Properly
Prior to parking the car, make sure the tire pressures are set to the door jamb sticker recommendation. Over-inflated or under-inflated tires risk developing flat spots from the stationary weight pressing in one spot too long.
6. Place on Jack Stands
If storing the vehicle for many months, consider placing it on jack stands to get the tires completely off the ground. This further reduces the risk of flat spots developing. Put a piece of wood or cardboard under the tires to distribute the weight if keeping them on the ground.
Just make sure the storage location is stable, level, and will not sink or shift over time as this could lead to the car falling off the jack stands.
7. Top Off Fluids
Check all other fluid levels before storage and top them off if necessary. This includes coolant, brake fluid, transmission fluid, power steering fluid and windshield washer fluid. Having the systems full will limit moisture accumulation and corrosion issues.
8. Clean and Protect Surfaces
Wash and dry the entire exterior of the vehicle before parking it. Treat any chrome or metal surfaces with a protectant. Vacuum and shampoo the interior carpets, mats and upholstery.
You can also use a product like Fluid Film to coat the underbody components and protect from rust and corrosion. Cover the vehicle with a fitted car cover for best results.
9. Prepare Registration and Insurance
Contact your insurance company ahead of time to switch to storage-only insurance or make necessary adjustments. Make sure the registration and annual state inspections will not expire while the vehicle sits idle.
Periodic Maintenance During Storage
Besides properly preparing the car for storage, some periodic maintenance steps are required over the following months to keep things in good condition:
- Check tire air pressures monthly and re-inflate as needed.
- Crank the engine over by hand at least once a month.
- Re-connect and charge the battery every 4 to 6 weeks.
- Add fuel stabilizer to the tank if storing over 6 months.
- Check undercar for leaks or damage from rodents/pests.
- Re-wash exterior if it gets dusty or dirty
- Make sure registration and inspection are up to date.
This periodic maintenance helps minimize battery drain, maintain lubrication, deter rodents and prevent fluid contamination over the storage duration.
Getting the Car Road Ready After Storage
Once you are ready to drive the car again after storage, some preparation is required to get it road ready. Here is a checklist of items to perform:
- Reconnect and charge battery if disconnected
- Check engine fluids and top off if needed
- Check tire pressures and inflate tires if needed
- Check brake pedal feels firm, may require bleeding brakes
- Wash vehicle exterior and vacuum interior
- Check windshield wipers/fluid and lights function
- Change engine oil and filter to flush contamination
- Drive slowly at first to circulate fluids and lubricate
- Get up to highway speed to test components at temperature
- Have it inspected if any problems arise
Following these steps will help transition the car back into reliable service after its long slumber. Be alert those first few trips for potential problems like leaks, abnormal noises, odd handling and warning lights.
Best Practices for Long-Term Vehicle Storage
Keep these best practices in mind when preparing your car for storage lasting 6 months or longer:
- Stabilize fuel and add antioxidants to oil
- Disconnect battery and store on trickle charger
- Seal or cover openings to deter rodents
- Inflate tires to proper pressures before parking
- Place on jack stands to avoid flat spots if storing over 6 months
- Top off all fluid levels before parking
- Wash and protect all surfaces prior to storage
- Adjust registration/insurance status as needed
- Periodically check over the stored vehicle
Proper planning and preparation will help keep your stored vehicle in good shape until it is ready for the road again.
Potential Problems When Letting a Car Sit
Despite best efforts to prepare and maintain a stored vehicle, some problems can still arise over time when letting a car sit unused. Watch out for these potential issues:
Dead Battery
Even disconnected batteries will slowly discharge over months of non-use. Extreme temperatures also hasten the rate of discharge. Attempting to start an engine with a dead battery can cause electrical system damage.
Rodent Infestation
Mice and rats are adept at finding ways to access parked vehicles. They can cause considerable damage by chewing through critical components while nesting.
Tire Flat Spots
The weight of a stationary vehicle can cause tires to deform slightly and develop flat areas on the tread. These are called flat spots and can lead to vibrations when driving.
Fuel Degradation
Old gasoline loses volatility and can gum/varnish the fuel system. Combustion properties also change as the fuel oxidizes. This can lead to hard starting and driveability issues.
Brake Rotor Rust
Moisture causes brake rotors to rust slightly over time when not used. This rust is normal but can initially cause some noise when braking after storage.
Battery Sulfation
Lead-acid batteries left discharged for long periods undergo sulfation. This leads to permanent loss of capacity over time. Maintaining a charge is key.
Coolant Breakdown
The additives and corrosion inhibitors in engine coolant have a service life. Long-term storage can lead to coolant acidity and less rust protection.
Sticking Brake Calipers
Brake caliper pistons can seize up if moisture causes corrosion during long-term sitting. This leads to a stuck brake and overheating.
Conclusion
Letting your car sit idle for up to 6 months is possible with some preparation and ongoing maintenance. The most important steps are stabilizing fuel, maintaining the battery, preventing rodent access, keeping tires inflated, and periodically starting the engine. Exercise caution when returning the car to service after long-term storage as well.
With proper precautions and maintenance, modern cars can generally sit parked much longer than 6 months without causing mechanical harm. But the risk of damage from dead batteries, contamination, leaks and pests starts to increase substantially past the 6 month mark for most vehicles.
