Because they're older, my in-laws have been in quarantine since early March and haven't driven their car at all. It's been sitting in the driveway in New Jersey (USA) the whole time, in mostly above-freezing and then warm and hot weather.

The car is a 2012 Subaru Forester and it's always been very reliable. Now it won't start, probably because the battery is dead. We could jump start the car, but if it does start and operate as normal, is there any other reason not to just drive the car for a while after that?

Some sources say to drain the gas and all fluids and replace them before driving, but that would be a lot more effort, obviously. Is it necessary to do so?


5 Answers 5


Cars are routinely left parked for three to six months or more without running, with no ill effects. I wouldn't hesitate to jump it and see if it'll start. As @BrianKnoblauch comments below, jumping a completely flat battery risks the alternator. The risk can be ameliorated by using a battery charger first, or leaving the jump battery and the to-be-jumped battery connected for a time, so the flat battery has at least some charge before the starter is engaged.

If the battery was old when the car was parked, however, the just-sitting may have pushed it over the edge into failure. That is, you might be able to jump it into running now, but the battery won't start the motor on its own the next time.

The low-tolerance-for-risk solution is to replace the battery. If you or your in-laws want to gamble on getting stuck, make sure the battery is fully charged, either with a charger, or by driving the car a significant distance. Without figuring alternator capacity, I'll guess that "significant distance" means an hour at engine rpm well above idle.

  • Given enough time, I'd charge the current battery on a charger, then see if it starts the car, as a test. Then try to remember when the weather turns cold that the battery may still be marginal if it starts the car in summer
    – Chris H
    Aug 20, 2020 at 10:56
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    You also risk the alternator by jumping a flat battery and then making the alternator work hard to recharge it. Alternators are meant to keep batteries charged, not bring them up from nothing. I'd definitely use a battery charger. Aug 20, 2020 at 16:14
  • @BrianKnoblauch A good point, thanks. I'll edit it into the answer. Aug 20, 2020 at 16:58
  • You can minimize the risk of getting stuck if the battery is toast by having your initial test drive be circling around the block x times before returning home to turn the engine off. Aug 21, 2020 at 13:49

If you have the ability and access to some tools, remove the battery and bring it to your local national auto parts chain ie: AutoZone, AdvanceAuto Parts, Oreillys etc. You may want to call first to see how they are handling this during Covid. They will charge and test the battery to determine its condition generally for free. This will take several hours or possibly overnight. Reinstall the battery. You may want to cycle the ignition key from "off" to "on" several times before attempting to start the vehicle. Start the vehicle as normal. Let it idle for a minute or two until the engine idles smoothly. Drive slowly (25-35mph) around the block for a few miles to warm everything up and get the fluids circulating. Gently apply the brakes several times to remove any surface rust from the rotors. If everything seems ok find the owners manual and check the maintenance records. If it is due for service based on time or mileage then schedule that service. It may be due for an oil change because it has been a year since the last one.

  • 6
    The issue with just jump starting is that if the battery is really dead it puts a lot of load and wear on the alternator to bring it to a full charge. Additionally you won't know the condition of the battery and if it will start the car the next time. If you have it charged, it can be tested and if need be a replacement can be purchased.
    – mikes
    Aug 19, 2020 at 23:30
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    Anecdotally, I have discovered during lockdown that once jumped my otherwise good condition flat battery needs a good half hour of driving every week to prevent it going flat again. That's now become part of my lockdown routine. No failures at all since I started doing this. I think my first run was an hour, but a half hour or so ever since has kept it reliable.
    – Tetsujin
    Aug 20, 2020 at 9:55
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    @Tetsujin similar here, only I'm lucky enough to have a 20W solar panel and regulator anyway. It's not going to give 20W on the dashboard, but it doesn't need to just for topping up. I can easily hear when the battery is weak, as a 2.4 litre diesel takes a fair bit of cranking
    – Chris H
    Aug 20, 2020 at 11:05
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    @ChrisH - Yeah. I don't have anything like that, though I do park right next to a service garage who have a nice jump starter. Normally they could full-charge my battery, but their 3-phase is down so no can do right now. I do appreciate the amount of power needed to turn over a big engine - 3L v6 here ;) I quite enjoy getting out of the house for a random direction drive to nowhere once a week though.
    – Tetsujin
    Aug 20, 2020 at 11:09
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    @ChrisH - it would be considerably more trouble than its worth on a modern 'all computer' car. No alarm, no motion-sensing camera, no locks, no clock, CarPlay, Bluetooth needs setting back up, etc It also really upsets the MIL. Even flattening it far enough that the electronics work, but then drop out as you attempt to start it means I need to reset half the above, then the MIL - for which I had to buy an app on my phone & a dongle for the car's diagnostic socket.
    – Tetsujin
    Aug 20, 2020 at 13:22

One thing I would do is check all the fluid levels before starting it, even if only to drive it to get it serviced. Also the tyres may need some air. My brake discs rust easily in our wet climate, so I know after even a few weeks to be wary of them at first. A few uses from very slow will tell you if they're OK and getting back to normal.

As I commented, I'd ideally charge the battery from a dedicated charger before starting the car with it. If it fails that test you definitely need a new one. If it passes, you still need to be careful when the weather gets cold as batteries don't like being kept discharged. Luckily failing to start is most likely when the engine is cold at home, reducing the chances of a stranding.

  • 1
    This is good advice, but a Subaru from 2011 will already do this for you. Just check the dashboard for any warning lights. If there are none, you're good to go. Cars include all that expensive tech these days for a reason.
    – user91988
    Aug 20, 2020 at 16:40
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    @user91988 does it actually check the levels and not just oil pressure/coolant temperature etc? The newest car I've ever owned was 2008, anything newer has been rented or borrowed; the work car from 2014 doesn't check everything as fully as you imply. I have a bit more experience of tyre pressure sensors - they're more of an alarm than a measurement, and a pain to reset, so better to check manually. Anyway I'd like to check before turning over the engine
    – Chris H
    Aug 20, 2020 at 16:56
  • Depends on how much time and effort you're willing to spend on something that's very likely to be just fine. (It's only been a few months...) I think most of us don't consider the risk great enough to bother. Cars are very well made these days, despite what old school gearheads want you to think.
    – user91988
    Aug 20, 2020 at 17:11
  • @user91988 10 minutes well spent if you ask me. The battery is key though as modern gadgets run them down faster when not in use, and being stored empty harms the battery
    – Chris H
    Aug 21, 2020 at 12:21

One other thing to check: regardless of the amount of gas in the tank:

Actuate the gas gap release lever NOW. You want to be sure the cap will open, while there is enough gas in the tank to get to a mechanic in case it doesn't.

My 2010 RAV4's release lever seized, after only 6 weeks of non-use at the start of the pandemic.

  • It's a good idea anyway to refill your gas tank while it's above a quarter tank to avoid a premature death of your fuel pump, which ought to be enough to get you to a mechanic.
    – Kat
    Aug 21, 2020 at 18:17
  • What a "gas gap release lever" and how to I find it on my Passat? (I assume it is not limited to LPG carsl Aug 22, 2020 at 18:19
  • Many North American cars have a locking cover over the gas cap. The cover is spring-loaded, and unlocked by tugging on a cable lever inside the car. Pull the lever, and the cover pops open, allowing you to unscrew the gas cap and fill your tank. But in Canada where I live, we get snow. And the city melts ice using salt. This means rust. And if the cable connecting the gas cap release lever to the cover gets enough rust, it will bind up. Not a problem if you are popping the cover every week or two as part of regular fill-ups, but...
    – d3jones
    Aug 22, 2020 at 19:11


First thing you do is throw the battery on a battery charger. These are simple machines with a red and black alligator clip, and a common electrical cord. They supply 12V-ish power, and have a voltage regulator so they will correctly charge the battery without overcharging.

A typical battery charger worth owning is 5-12 amps in normal mode. (may also have a ~2A slow charge mode and a 20-60A boost mode, but you want normal mode).

More amps never hurts, but it costs money, and you don't really need more. Slam-charging a battery with lots of amps will prematurely age a battery.

A typical battery is 80 amp-hours new, so you can do the math on that, it may take 8-15 hours to fully top up the battery.

Allowing a battery to go stone dead is also bad for the battery and will age it somewhat. Car batteries are very, very bad at deep cycling (being run down dead then fully recharged).

Unfortunately, lots of things reduce their life. Using them, not using them, overcharging, letting them go flat, looking at them cross-eyed... generally if a car battery is older than 5 years, it's on borrowed time. So if an old battery has gone dead, you can try to save it with a slow (~10A) charge, but be prepared to say goodbye.

Is that a terrible battery design? Oh you betcha, but it's cheap, and it's good at one thing: the huge surge of energy needed to start an engine. You can get a 40-year battery that weighs 500 pounds (nickel-iron) or 500 dollars (nickel-cadmium e.g. airplanes), and lithium batteries show some promise but they're expensive too.

Fuel and consumables

For a storage period of months, you really don't have much of a worry. The worst problem you will have if your area has winters, is "winter fuel" vs "summer fuel", which has different boiling points; just put fresh fuel in there when able.

Even out to a year, this won't be a worry.

Once you're out past two years, you have to start worrying about the fuel turning into varnish in the tank and equipment. Ask anybody who started up a lawnmower that's sat for 10 years, you can spend an hour chipping varnish out of the carburetor bowl. And those are super simple carbs.

These days, everything is fuel injection. Varnish will break the fuel pump, plug filters, plug lines somewhat, and mostly, plug fuel injectors which are extremely fine because they make a fine mist of fuel. Fuel injectors can be sent out and cleaned.

Another issue is the 10% ethanol in the fuel breaking down and turning into stuff that is corrosive, which can then rust the tank interior and in particular, the delicate brass electrical connections for the fuel pump and fuel gauge sending unit.

Watch for coolant problems

The other issue with extended storage is coolant. It doesn't evaporate, but rubber hoses can rot or be chewed by animals who are making their home under the car since it never moves. This can cause a leak, either immediately or later when the system pressurizes. As such, once you get the car going again, it's easy to accidentally run the car with no coolant in it. The car won't tell you anything until it overheats, by which point damage is starting to be done. Unfortunately most people do not take overheat warnings seriously, and continue driving "because what else can I do?" This will warp the cylinder head, greatly increasing repair costs... and eventually reduce the engine to slag.

What you do is pull the car over as soon as practicable, let it cool down for 1/2 hour, then try adding water if you have any... and if you are able to refill it and the leak is slow enough, try limping it to a nearby place it can be serviced, again shutting off and letting it cool if the overheat light returns. Sometimes that works, sometimes it doesn't. If that is not viable, then just have it towed. It's cheaper than resurfacing a head.

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