What's the minimum amount of activity my car needs to start in 6 months?
January 23, 2011 5:59 AM   Subscribe

I'm subletting my house for 6 months and need to leave my car in my garage for that period. My tenants have offered to start the car periodically the keep the battery running. The car is not registered, so they won't be able to drive it more than a few feet on driveway (backing out and driving back in). Is this amount of activity enough so that the car will be functional when I return? Or do I need to take more extensive storage measures (e.g. disconnecting battery)? Thanks!
posted by franciskelly to Travel & Transportation (8 answers total) 3 users marked this as a favorite
Disconnect the battery, and put fuel stabilizer in the gas tank (you'll want 3/4 - full tank of gas).

Should be fine 6 months later.
posted by gatsby died at 6:06 AM on January 23, 2011 [1 favorite]

You could invest in a trickle charger which will keep the battery charged. Flat spots on tires after six months?
posted by fixedgear at 6:26 AM on January 23, 2011

If you're going to start a car that's being stored, it should be driven enough to get sufficiently warm, otherwise the moisture that is created remains in the exhaust system and contributes to rust.

gatsby died is right, fill the tank, put the appropriate amount of fuel stabilizer in it, drive at least 50 miles on that tank of gas (to make sure the stabilized fuel gets to the carb/injector (whichever) system. Then, park it. Instead of disconnecting the battery, I would put a trickle charger on it.

Be sure to change the oil when you get back, check all the fluids, tire pressure, etc. you should be fine.

I store my motorcycle and boat using these techniques, (damn michigan winters!) and they do well.
posted by HuronBob at 6:29 AM on January 23, 2011 [1 favorite]

The proper way to do this is to put stabilizer into the (full) tank, disconnect the battery, and put the car up on jackstands/blocks/boards to avoid flat spotting the tires. This would only take you <1>
On the other hand, if you are really only going to be gone 6 months, the lazy man in me would just disconnect the battery and call it good. Especially since you'll be starting the car again in nice warm weather.
posted by no1hatchling at 8:06 AM on January 23, 2011 [1 favorite]

I regularly store my vehicle for 5 months (in winter). Disconnecting the battery should be enough, although a trickle charger wouldn't hurt. As for the tires, I overinflate them to avoid flat spots and it has worked so far. Make sure to reduce the pressure when you're ready to use it again.
posted by bluefrog at 8:46 AM on January 23, 2011

At a minimum, disconnect the battery. Or purchase a float charger- this would be preferable, since it will keep the battery charged and you won't lose your radio presets.

I would also change the oil before you leave. Used oil has all kinds of awful things in it that would preferably not be in your car gunking things up. I would use a fully synthetic like Mobil 1. Synthetic because it is less likely to gum up. (Not in the pan, but the film that remains on the internal parts. Synthetic is more stable and has fewer VOCs to evaporate.)

Fuel stabilizer couldn't hurt, but it isn't necessarily necessary. (I think the problem is that there is the possibility of the gas getting contaminated with bacteria that will ruin it. If that doesn't happen and the fuel system is closed, the gas will not go bad.)

If you have the ability, jacking it up isn't a bad idea. 4 ruined tires will cost a lot more than a ruined battery. I would also soak the tires down in a protectant like Armor All. No idea if this is true, but it seems like a tire that is just sitting there would be more likely to go dry-rotted. A set of jack stands isn't all that expensive. Metal milk crates or railroad ties are also time-honored solutions.

Make sure the car is more or less dry inside- maybe put in one of those pails of basement dessicant. A sealed up car full of humidity will tend to oxidize stuff.

Set the HVAC on recirculate so bugs don't get in the HVAC system.

If critters are a potential problem, keeping the hood open might keep them from building nests. Maybe remove the air cleaner assembly and tape it off.

Make sure the coolant and wiper fluids are topped off.

Short answer: unless your tenants can take the car out and get it up to operating temperature, starting it up will cause more damage than it prevents.
posted by gjc at 8:49 AM on January 23, 2011 [1 favorite]

(I think the problem is that there is the possibility of the gas getting contaminated with bacteria that will ruin it. If that doesn't happen and the fuel system is closed, the gas will not go bad.)

No. Bacteria is not an issue. Gasoline is volatile, and in an unsealed container, some of its components will evaporate, while others can oxidize. Filling the tank before storage does help, because it minimizes the air that supplies Oxygen and allows evaporation.
posted by Kirth Gerson at 9:03 AM on January 23, 2011

Bacteria is really only an issue if it's diesel fuel.

Filling the tank avoids leaving sides of the tank exposed. On which moisture can condense and contaminate the fuel. But only if the tank is vented, most auto tanks aren't any more. Condensation is bad, even more so lately due to ethanol being added (a huge boondoggle).

Air in the tank isn't going to 'allow' evaporation, that would only happen if the tank was left open. The amount of oxidizing that might occur is minimal, if any at all. That's what the stabilizer helps manage.

I have to deal with this issue for two 110 gallon tanks in my boat, every winter. The proper method is fill the tanks, put in stabilizer and run it about 15 minutes to circulate it. I typically take the boat to the pumps, fill the tanks, add the stabilizer and take one last right back to the marina. At which point I change the oil and run antifreeze through the seawater cooling lines. All I have to do the following Spring is open up the seawater cooling lines, start the engines and go.

I'd consider putting a breathable cover on it, even if it's stored inside. That would help keep crud off the paint. Then leave a window or two cracked open to allow air to circulate. This would depend on the climate in which it's being stored.

You really don't want to leave a car in a dark, dank place because mold LOVES to grow on leather seats and other interior surfaces. Frankly, it'd be less troublesome for it to be out in the sun than someplace like a clammy, cold basement garage.

You disconnect the battery in order to avoid having the radio and other devices drain it. They pull a really small charge to keep their memory (like your radio stations) active. This isn't a problem if it's only a few weeks, but more than 3 months will likely kill it.

Tires can develop flat spots over time. If your tires are relatively new and properly inflated it's not likely to be a problem. Check that they're properly inflated before storage. Maybe inflate the a little more than usual. And make sure you re-check the pressure when you return. Unless they're actually going to drive the car around it's not likely they'd avoid the tire problem. Just rolling it out and back in would likely leave the tires right back where they started.

So for your car I'd go with a) oil change, b) fill tank, c) add stablizer, d) put it in the garage and e) disconnect the positive side of the battery.

Finally, check with your insurance about how the vehicle is covered. What if it's stolen? Or damaged? Or misused by someone else and involved in an accident? Make sure your coverage adequately addresses the risks.
posted by wkearney99 at 6:55 PM on January 23, 2011 [1 favorite]

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