"Does gasoline go bad after a time?" Topic

As part of my swine flu/Canadian blizzard prep, I bought a small jerry can and filled it with gasoline. Might be useful if gas supplies are interrupted or if someone (ahem) forgets to gas up.

My plan was to simply use the gas periodically and then refill the can. My question is: how long does gas keep its "pep"? Should I replace it every six months? Does gas last forever?

I'm sure my dad would know the answer to this, but I'm not really up for three choruses "don't they teach kids anything?" So I throw myself on the mercy of the TMP crowd.

thanks kindly

Bob in Edmonton

Is where it's stored subject to extremes in temp?

Thanks,

John

Your dad's answer could be out of date, as well. "Gas" is a complex combination of titanic molecules, most of which are pretty eager to be other kinds of molecules, which is how they make the car go. Some of these will break down on their own in months, possibly into other molecules that could gum up your fuel injectors or combust into something that will gum up the catalytic convertor.

Or not.

I don't know.

But wherever you get your answer, you should require a pretty good reference or source, because it's not an easy one.

Andrew

My gas-powered lawn equipment seems to think so if I try to use last years gas in the springtime…

I think there is an evaporation issue that changes the chemistry of what remains.

I suggest typing "does gas go bad" into google.

Why take a risk? Just put it in your car every three months or so and replace with fresh.

I heard about gummy residue in old petrol, but don't know much about it. The stuff is way too expensive to just have extra of around the house.

Petrol (as it is properly called!!) has got numerous additives in it designed to help keep the engine clean etc. These are more likely to go off than the actual petrol itself in the short term. Also it is fairly hygroscopic and will soak up moisture quite readily causing missfires. You should be OK if it's tightly sealed for a couple of months depending on storage conditions.

Yes it does, just not sure how long. Best to just use it periodically and get fresh as needed.

You can also buy a stablizer to add to the gas to keep it 'fresh' longer.

I read in the manual for my gas lawnmower that gasoline can go "stale" and will reduce performance.

Thanks for your collective responses, excepting perhaps Hexxanhammer's (not sure whether the google suggestion is as annoying as three choruses of "don't they teach kids anything, these days'" but it is close, so good job there!).

Yes, I googled but the results were vague and inconclusive, mostly written by staff writers at CNN recycling last year's copy. Hoping for the more practical, hands on advice I got here.

The collective wisdom of the neighbours appears to be run along Gungir's and Napthyme's line, suggesting cycling it every three months or so even though stored in a sealed, airtight container. Not sure where that leaves us when the end times come, though… walking, I guess!

Well, I know from sad experience that if you leave a car sitting long enough the gasoline in it will "gum up" and freeze the fuel pump and other parts, requiring an expensive repair that may turn out to be more than the car is worth, even though it is in otherwise excellent condition, in which case you donate the car to a local rural high school's shop class and take joy from later hearing how excited the students were to get to work on "a really cool car." Lesson learned, but with a decent reward at the end.

Gasoline does go bad over time. Pre the addition of methanol to the formulation, gasoline could be expected to last at least 3 years without the addition of a stabilizer (as Evil Bob stated). Although you may have seen some degradation of octane level the last year. After the 3 years or so, to octane levels really start to drop off until it's pretty useless.

I haven't seen anything since we've begun adding methanol to the formulation; however, it is well known that methanol and gasoline will separate into two phases in fairly short order. Which is why the methanol is not added to the formulation in pipelines, but at the Terminals.

So I would not expect modern gasoline to last very long without having to decant the methanol from the top of the can, which takes us back to octane degradation issues.

But I wouldn't keep gasoline in a container (if for a car or generator) for more than six months, if that long. It may burn, but how well is going to be key.

PS: Don't shake up the container hoping to mix it back up and then open the container. Unless you're trying for a Darwin Award.

My lawnmower mechanic told me that modern gasoline has a "shelf life" of c. one month; after that it starts to break down. But I keep containers of gasoline over the winter and use in the following spring, so far without any trouble. So the "breaks down" must be rather slow….

In July, I used up the last gasoline from the 100 gallon bulk tank that my Dad had filled up in Spring '08. He added stabilizer to it. It worked just fine.

I would, however, echo the recommendation that you periodically use/refill that jerry can until the zombie apocalypse strikes.

You will find WalMart and automotive stores sell stabilizer additives that do help extend the storage life of gasoline. However, one of the most important things you can do to help prolong its lifespan is not store the fuel in hot locations, especially where the container is exposed to sunlight. Keeping stored gas cool (5-10 degrees above room temperature) can make the fuel last several months longer than fuel stored in 90+ degree heat.

I will definitely have to look into stabilizer.

I don't store a LOT of gas between lawn seasons, but when it does go bad, or stale, I have a problem disposing of it.

Stabilizer would solve the problem.
Thanks all.

when it goes bad you will have problems starting small engines or very cold big engines with it but you can use a spray can of cold start to over come it. once its started and hot it will run just fine on the old gas.

you can also mix the old gas with new gas 1 to 1 to bring it back to being useable.

I have been told by various Logistical types that gas/petrol does lose some of its performance qualities if not used over a period of time. No one however could tell me what that period of time was.

And from the FWIW department I have never seen an expiration date on a pump at the gas station yet.

VR
James Mattes

Just put it in your car every three months

Three months is close to the limit without a stabilizer. I'd never leave gas for that long.

Where we use snowblowers in winter and lawnmowers in Summer, many Northern North Americans know lots about this stuff.

Go to Crappy Tire and ask for stabilizer in the auto section. It doesn't take much.
--
Tim

Interesting idea for some post-apocalyptic wargaming there – any idea if bulk storage like filling station tanks would fair any better (maybe due to proportionately less evaporation). Otherwise, when Mad max's bus gets to its destination they could be in for a disappointment.

The more volatile hydrocarbons evaporate. What was left was varnish if it got left long enough. Used to have to tear down carburetors and clean them when working over old cars. Insofar as storage, I pulled this off a web page on two cycle engines -

Gasoline shelf life: According to Chevron…. "Gasoline stored in a tightly closed container in a cool place will stay good for at least a year. It is better if the container or gas tank is almost (95%) full. If the container or gas tank will be in the direct sun or will be heated above 80 degrees F. much of the time, add an aftermarket fuel stabilizer to the gas when you first buy it. Gasoline-oil blends for two-stroke cycle engines stored under the proper conditions will keep as well as gasoline itself."

And this from Shell…. "All gasoline has finite storage life. If storing gasoline longer than 6 months, you may want to use a supplement fuel preservative additive.

The author of the page (http://www.sschapterpsa.com/ramblings/gasoline_oil.htm) states that he believes that the varnish formation was exacerbated by the old lead additive. I have seen it in unleaded as well.

Sta-bil is the answer.

I consider six months to be the maximum safe unstabilized storage time in New England's climate, but I've seen it go considerably longer w/o destructive consequences.
-Kle.

"And from the FWIW department I have never seen an expiration date on a pump at the gas station yet."

Considering the USTs are re-filled at least weekly if not more often at most stations, you never will.

Depending on location relative to travel and commute corridors, a gas station can potentially see the filling truck daily. Since most gas goes into automobiles and will be burned within two weeks, expiration isn't an issue.