28/12/2017
Leaving Your Car Idle: What You Need to Know
It's a common concern for car owners: what happens when your vehicle is left stationary for an extended period? Whether it's due to a change in circumstances, a planned holiday, or simply a lack of need, the question of how long you can leave a car without driving it, and whether it's truly okay to leave it unused for two months or more, frequently arises. While the short answer is yes, it is possible to leave a car untouched for a couple of months, or even longer, without major incident, it's crucial to understand that this isn't a 'set it and forget it' situation. To ensure your car is ready and willing to go when you need it next, a number of proactive maintenance tasks need to be carried out periodically. Ignoring these can lead to a host of problems, from a dead battery to more serious mechanical issues.
The Battery: The Heartbeat of Your Car
When considering how long you can leave your car without starting it, the primary factor is the condition of its battery. Modern car batteries and their sophisticated electrical systems mean that most vehicles can happily sit for a couple of weeks without needing to be at least turned over to recharge the battery. However, 'happily sit' is a relative term. Even a healthy battery will gradually discharge over time. If you're unsure about the health of your battery, or if your car is nearing the end of its typical battery lifespan (usually 3-5 years), it's best to err on the side of caution. Starting the car and letting it run for around 15 minutes is a good way to ensure the battery gets a decent charge and to keep the engine's fluids circulating. Doing this weekly can make a significant difference in preventing a flat battery.
Essential Checks Before Resuming Driving
If your car has been sitting idle for a while, and you've been diligent about starting it periodically, it should generally be fine. However, there are a few key areas that warrant a closer inspection before you embark on your first journey after a period of inactivity. One of the most common issues you might encounter is with your tyre pressures. Tyres can lose pressure over time, especially when a car is stationary, leading to flat spots and an uneven ride. It's essential to check and adjust your tyre pressures to the manufacturer's recommended levels. You might also notice some surface corrosion on the brake discs. This is typically harmless and will usually clear after a few applications of the brakes. Nevertheless, it's wise to allow additional braking time and space during your initial drive, as the braking performance might be slightly compromised until the corrosion is worn away. Always pay close attention to any warning lights that illuminate on your dashboard before you take your vehicle out for the first time after a lay-up. If any lights appear, it's advisable to book a car repair with a qualified mechanic to diagnose and address the issue before it escalates.
Top Tips for Laying Up Your Vehicle
If you anticipate leaving your car parked up for a month or more, adopting a few preventative measures can save you a lot of hassle down the line. Here are three crucial tips to keep in mind:
- Fuel Up Before Storing: Top up your fuel tank before you lay up your vehicle. A full tank is beneficial for two main reasons. Firstly, it minimises the amount of air in the tank, reducing the potential for condensation to form. Water in your fuel tank can lead to a range of issues, from corrosion to fuel system contamination. Secondly, it helps to prevent the fuel itself from degrading and losing its efficacy over time.
- Prioritise Battery Maintenance: As mentioned earlier, battery maintenance is absolutely vital if your car is to be left stationary for much more than a fortnight. The best practice is to run your engine for a good 15 minutes at least once a week. This ensures the battery gets a chance to recharge and that the engine's lubrication system is adequately circulated. Alternatively, and often a more reliable solution for extended periods, is to use a mains-powered battery maintainer (also known as a trickle charger). These devices constantly monitor and maintain the battery's charge level without overcharging it, keeping your battery in good condition and your engine ready to start.
- Fuel Degradation: While petrol can stay fresh in a sealed container for around a year, its stability in a car's fuel tank can be less predictable. If exposed to air, petrol can begin to degrade in as little as a month, leading to starting problems and poor engine performance. For diesel vehicles, the situation requires a slightly different approach.
Diesel Car Considerations
Diesel cars require a bit more careful management if they are going to be left idle for an extended period. In our experience, summer diesel is far more susceptible to waxing when the weather turns cold than winter diesel. Fuel specifications change throughout the year, and diesel fuel can begin to form a waxy substance in colder temperatures, which can clog fuel filters and lines, preventing the engine from starting. It's important to be aware of the type of diesel you have in your tank and the potential weather conditions. If you know your car will be stored through a cold spell, using a diesel additive designed to prevent fuel gelling can be a wise investment. For longer-term storage, consider using a fuel stabiliser, which helps to prevent the fuel from degrading and absorbing moisture.
What About Tyres?
Beyond just checking pressures, prolonged periods of inactivity can cause tyres to develop flat spots. These are areas where the tyre has been consistently pressed against the ground in the same spot. While minor flat spots might disappear after driving, more significant ones can affect the ride quality and even the tyre's structural integrity over time. If you're storing the car for several months, consider placing the vehicle on axle stands. This takes the weight off the tyres and prevents them from deforming. If this isn't feasible, ensure you move the car slightly every week or two to change the contact points of the tyres on the ground.
Other Components to Consider
While the battery and tyres are often the primary concerns, other components can also be affected by prolonged inactivity. The engine oil, for instance, can degrade and lose its protective qualities. Running the engine periodically helps to circulate the oil and keep it fresh. However, if the car is stored for a very long time (over a year), it's good practice to consider an oil change before putting it back into regular use. Similarly, brake fluid can absorb moisture over time, which can lead to corrosion in the brake system. While this is a slower process, it's worth noting for very long-term storage. Antifreeze in the cooling system can also degrade. Ensuring your coolant is topped up and in good condition is essential, especially if the car might be exposed to freezing temperatures.
Summary Table: Car Storage Best Practices
| Period of Inactivity | Recommended Actions |
|---|---|
| 1-2 Weeks | Start and run for 15 mins (optional, but good practice) |
| 2 Weeks - 1 Month | Start and run for 15 mins weekly. Check tyre pressures. Fill fuel tank. |
| 1 Month - 3 Months | Use battery maintainer. Fill fuel tank. Check tyre pressures. Move car slightly weekly if no battery maintainer. |
| 3+ Months | Use battery maintainer. Fill fuel tank with stabiliser. Consider placing on axle stands. Check all fluids. |
Frequently Asked Questions
Q1: How long can I leave my car parked without starting it?
Most modern cars can sit for about two weeks without needing to be started. However, for longer periods, regular starts or a battery maintainer are recommended.
Q2: Will my tyres go flat if I leave my car unused?
Tyre pressures will likely decrease, and flat spots can develop if the car is left stationary for extended periods. Regular checks and pressure adjustments are necessary.
Q3: Is it bad to leave a full tank of petrol in the car?
No, leaving a full tank of petrol is actually recommended when storing a car for an extended period, as it helps prevent condensation and fuel degradation.
Q4: What happens to diesel if left for a long time?
Diesel can degrade and, in cold weather, can 'wax up' or form a gel-like substance, clogging the fuel system. Using fuel additives or stabilisers is advisable.
Q5: Do I need to do anything special for a diesel car stored in winter?
Yes, it's crucial to use winter-grade diesel or add a diesel anti-gelling additive to prevent the fuel from solidifying in cold temperatures.
Expert Advice
For more detailed information on essential maintenance tasks required before laying up your car for an extended period, it's always best to consult with the professionals. Getting in touch with your local garage and speaking with a member of their experienced team can provide you with tailored advice for your specific vehicle. If your tyres require attention, many reputable garages and tyre specialists, such as Protyre, carry a wide range of tyres from leading manufacturers like Falken and Sumitomo. With services like same-day fitting available on many of their tyre ranges, you can often purchase online for the best prices and have them fitted quickly, ensuring your vehicle is road-ready.
If you want to read more articles similar to Car Unused: How Long Can It Sit?, you can visit the Maintenance category.