Leaving a car idle for more than four weeks is generally not recommended. Beyond this point, you risk serious and potentially expensive problems, primarily with the battery and engine components. The biggest immediate threat is a dead battery, as all modern vehicles have a small constant electrical drain. Fluids can degrade, tires can develop flat spots, and moisture can accumulate in the fuel system and exhaust.
For shorter periods, up to a month, your car will likely be fine. However, proper preparation is key for any extended parking. If you know your car will sit for a long time, taking a few simple steps can prevent most issues.
The most critical step is addressing the battery. Simply starting the car and letting it idle for a few minutes is not enough to recharge it and can actually cause moisture buildup in the exhaust system. For idle periods exceeding one month, using a battery maintainer (or trickle charger) is the best practice. This device plugs into a wall outlet and connects to the battery terminals, providing a small, steady charge to keep the battery at optimal voltage indefinitely.
Other factors to consider include fuel stability. Ethanol-blended gasoline can absorb moisture and degrade over several months. Before long-term storage, filling the tank with fuel and adding a fuel stabilizer can prevent varnish and gum deposits from forming in the fuel lines and injectors. Inflating tires to their maximum recommended pressure can also help prevent flat spots from developing.
| Potential Issue | Typical Onset Time | Preventive Measure |
|---|
| Dead Battery | 2 - 4 weeks | Use a battery maintainer or disconnect the negative terminal. |
| Tire Flat Spots | 1+ months | Inflate tires to maximum pressure on the sidewall. |
| Fuel Degradation | 3 - 6 months | Fill the gas tank and add a fuel stabilizer. |
| Engine Oil Degradation | 6+ months | Change the oil before storage or immediately upon returning. |
| Fluid Evaporation | 6+ months | Check all fluid levels (coolant, brake) before and after storage. |
| Brake Rust | 1+ months | Apply parking brake lightly or use wheel chocks (not both). |
