Letting a Car Sit for a Week? What Can Happen?

Whether for a vacation trip or a business event, there are times when we have to leave our cars unattended for a longer period. Understanding what may happen to it is the best way to prevent the most common problems

Is it Bad to Let a Car Sit for a Week?

It is not advisable, for sure. Modern cars are designed to be a part of your routine, whether on long or short trips, so they work at their finest when used at least once a day.

On the other hand, their projects consider, indeed, the possibility of going through a long time without use. After all, that is also part of our routines: sometimes we go on a trip, we may leave the car to be serviced, etc. Letting the car sit for a week will only become a problem if you neglect it, that is if you simply park it and leave.

Also read: Letting a Car Sit for a Month? 6 Things that Can Happen

Can Car Battery Die After a Week?

Yes, it can. When the engine is turned off, the battery is the sole responsible for all electrical demands in the car, so there will always be some consumption even if the car is turned off. As a result, the battery will, indeed, die eventually. But there are more variables to consider here.

Cold weather is known to be harmful to batteries. They take longer to charge and, the more directly exposed they are, the harder it is to revive them later on. In extreme cases, such as wintertime in cold countries, one week may be enough to render the battery unusable.

Another important issue is called “parasitic drain”. If the electrical connections in a car are not properly grounded, it might have an unwanted connection that continuously drains energy. That is harmful both in the short term because it keeps consuming energy, and in the long term, because it affects its capacity to hold charge.

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The best action to take in this regard would be starting the car every once in a while to keep it idling for some minutes. That would mitigate the effects of low temperature and would activate the alternator, which quickly recharges the battery. Then again, doing so means that you would not be leaving the car unattended; the situation is more favorable than the one we are considering.

Some other variables are obvious, but important to keep in mind nonetheless. All batteries lose capacity as they age, so the older your battery is, the more likely it will be to die in a week. It also goes without saying that forgetting the lights and/or the radio on will drain it much faster.

Can Tires Go Flat After a Week?

Yes, they can, because no tire has perfect sealing. Even though the car leaves the gas station or the repair shop with the tires at the recommended pressure, it will continuously drop because there will always be some volume of air escaping from the tire.

When the car sits for a long period, tire pressure will keep dropping without you being available to have it restored at a gas station, for example. In other words, the pressure will always be lower than when you left the car. Depending on the period, it is even possible for them to get completely flat.

High-quality tires are supposed to have better sealing, but that can only slow down this process, never prevent it from happening. On the other hand, if your car has low-quality and/or simply old tires, it may have internal cracks which make it easier for air to leave the tire.

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Does Oil Go Bad Sitting in an Engine for a Week?

Yes, it does. Every time oil stays still inside the engine, it begins to decant. In other words, some of its components separate from the others. In short, this is dangerous because, once the engine gets back to work, it will start pumping only part of the oil components at a time.

If the oil was already old, it is probably already contaminated with residues from the metallic components of the engine; those would be concentrated at the bottom of the oil volume, so the initial pumping would get a much higher concentration of solid particles in the fluid. That is likely to scratch the components and even clog some ducts.

Since there will always be oxygen inside the engine, the oil will always be in contact with it. Another problem appears here because, when oil spends a long time without movement, it becomes more vulnerable to oxidation from the top of its volume, where it is in direct contact with oxygen. That is another way to have its properties negatively affected.

Last, but not least, oil always retains water to some extent, generally from the vapor present in the air. Water is heavier than oil so that decantation would concentrate all retained water on the bottom of the oil volume. Once the engine starts running again, there would be pure water flowing for a moment instead of oil, and that would be highly damaging as well.

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Where to Leave Your Car if it Sits for a Week?

The best option is a garage, so it would be protected against weather conditions (rain, hail, etc.) and extreme temperatures. It is also advisable to use a car cover even in that case in order to prevent pests from getting inside it. The better the car’s condition is when you leave it, the fewer additional precautions you will need to take.

When it comes to fuel, it is recommendable to fill the tank, in order to slow down oxidation inside the tank and add some stabilizer fluid to prevent the negative effects of fuel aging. The car will still not work properly afterward, because it will be consuming old fuel, but the effects will be less noticeable.

If you are leaving the car in a cold place, and/or suspect there might be some parasitic drain, it will be advisable to disconnect the battery altogether and store it in a warmer place.

When it comes to the tires, you should keep them at the recommended pressure or even a little higher when storing the car, so there will be lower chances of having them flat when you come back.

Finally, you should also replace the oil right before storing the car. It will still suffer negative effects, such as oxidation and the separation of some components, but they are expected to be less significant in new oil.

How Long Usually Can a Car Sit without Any Problems?

A couple of days. City cars are designed to be used every day, so that is the frequency at which they show their best operation. It is possible to leave them unused for longer times, of course, but the longer this time is, the more actions you will have to take in order to avoid or mitigate problems.

The rule of thumb here is to start by learning what happens to an unattended car as time passes. There are many problems that can happen, but some only become concerning after longer periods. Preparing the car to sit for a week is definitely not the same as preparing it for six months, for example.

Nevertheless, you have to keep in mind that any long periods will be harmful to some extent, even if you prepare the car. Therefore, the best you can do is check on it every once in a while, if possible, and drive it for some minutes. That will mitigate the effects of sitting still and will give you periodic opportunities to check if any other interventions are needed.