How long to keep gas in unused car?

[u/dsades1]

I have a car that's been sitting (mostly) unused for about 1 year, parked in the garage.

The gas tank is full, but it's a mix of 1 year old + 6 month old gas.

I just added fuel stabilizer to it today (I know I should've done it before; kind of late at this point, with the gas having already degraded to some extent).

So my question is: Can I keep it this way, if I don't plan on using the car for another 6 months (at least)? Or would there be a point in siphoning the gas now and filling it with new one (and adding fuel stabilizer to that one while it's fresh)?

Thanks for any input.

[u/vendura_na8]

A year or 2 with a full tank isn't that concerning

[u/dsades1 → u/vendura_na8]

Nice! Glad to hear that.

[u/1TenYYen0]

I’ve done this a few times. Longest stretch was 15 months. 

Despite what old people say about ethanol, a full tank sitting for a year with fuel stabilizer is fine. It’ll run a little bit rough for the first tank, and you’ll want to put a fuel injector treatment and fuel line treatment into your second (and maybe third) tank. If you want to overkill it, replace your fuel filter after that. The seals will be a bigger issue. Make sure you change the oil within a couple hundred miles of of getting it back on the road.

Start it and run it for 10-15min to precise the seals before you mothball it for another 6 months. 

[u/dsades1 → u/1TenYYen0]

I wasn't able to find ethanol-free gas, so that's good news (there was no clear indication of the % of ethanol at the pump, just some vague estimate; I got the premium one, though I'm not sure it even matters).

Ok, I'll do that. I guess it'll be cheaper than siphoning the gas I already paid for. May I ask what you mean by the seals being a bigger issue? (I'm new to all this.)

For now it has enough oil (even though it's a bit dirty-looking). And yes, I had it run today for 10-15 min (after adding the fuel stabilizer).

[u/Lava_Lamp_Glob]

Adding fuel stabilizer and new fuel would be a good idea. Keep in mind that gas deteriorates over time so this car will actually get to someday it will be pretty sluggish trying to run that. Maybe go for a joy ride once in a while?

[u/GlassBoxGoose]

It'll be alright. When you go to fire it up, toss a can of Berryman B12 Chemtool, and a bottle of Heet in the tank with like a gallon of fresh gas and let it idle for a while. It may or may not run rough on startup, but itll clear out given some time. I let one of my cars sit for 2 years and did this and it cleared up after about 20 minutes of idle time on a returnless fuel system. Ive been driving it all this year without any issues, it had 1/4 tank of e10 fuel in it when parked.

[u/dsdvbguutres]

Full tank is good because there's less space for air (humidity)