MGB & GT Forum

Lots of MGB owners do not drive their car that often...
For how Long Can You Store Gasoline, before it goes bad?



Edited 3 time(s). Last edit at 2024-05-19 11:45 AM by ski.dive.

This seems to be common advice on Google:
three to six months
In general, pure gas begins to degrade and lose its combustibility as a result of oxidation and evaporation in three to six months, if stored in a sealed and labeled metal or plastic container. Ethanol-gasoline blends have a shorter shelf life of two to three months.

A fuel stabilizer can extend the time.

I am sorry but gasoline lasts longer than that. Sure, pure gas lasts longer than corn, but both last longer than what is spouted by google.

We use to take gas that had been sitting in motorcycle tanks for 3-5 years and dump it in our trucks and drive on. We did this because the gas that sat in the carbs and fuel pumps would gum up and have to be cleaned out.

Every year I would buy corn blended gas and mix it with oil for our weed eater. The gas remains I. The tank for the entire winter, and would start up the next spring.

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I would never join any club, that would have me as a member. - G. Marx

One has to ask, if everyone says that gas is only good for 2-3 months, why do those same people suggest topping off the tank before Winter storage? Rhetorical question. No need to answer. The internet is filled with all kinds of answers.

I have used E10 fuel for over 40 years. That's all that was commonly available around my home. It used to be called gasahol. I do use old gas that is easily 2-3 years old. I usually mix in fresh gas. I did this with a 5.0L Mercruiser that was stored for several years with a half tank. I just topped off the tank, maybe 30% new vs 70% old. I have kept several gallons of gas in a portable generator for a couple of years. I occasionally started it with the old gas and it never failed to start or run well. After a couple of years, I drained it and mixed it with some fresh gas to use in my lawn tractor. I never had a problem. I would not try to start an MG on 10 year old gas though.

I just drove my roadster using E10 premium at least a year old. The tank is almost empty so it will get fresh fuel soon, but ran amazingly well. I didn't do a high speed run or pull any steep hills so there may be some performance degradation that I couldn't detect. I have had problems in the past with 18 month old E10. I drove the GT on E10 regular from last September or so. It will get fresh soon though because I use fuel from it for the lawn mover and rototoller. I think there must be variations in fuel longevity based on variables like storage, humidity, and local formulations because I can't deny others seem to have a lot more problems than I do.

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"If I knew where the good songs came from, I'd go there more often."

Leonard Cohen

I store my cars for 5-7 months every year using fuel stabilizer, and have never had a problem starting It does take a half hour of driving to get rid of the flat spots on the tires.

The 6 month answer is about right for ethanol free gas. But hidden in the question is the definition of "lasts". How long does it last in what state? Can gasoline, without stabilizer, actually run a car after 6 months? Sure. My '79 Mustang sat in the bask yard in Alaska for 11 years before I revived it and sold it. No fresh gas. Fired right up, did nice second gear burn outs. But that doesn't mean it should last that long, or that the gas would not cause issues very soon due to its age, lack of volatiles, water content, and whatever.

During desert conflicts in WWII, fuel dumps were limited to diesel because a drum of diesel could be kept or buried for a year or more without ill effect, gasoline not so much, especially in the desert. Aviation gasoline in WWII was not stored for long at all, but was flown in to advance refuel sites just about daily because by the time it got anywhere near the front, it was already several months old.

So you can argue that gasoline can be stored for more than 6 months, but with the additives used these days to reduce pollution, the gas loses it usefulness quickly unless you use a stabilizer.

So why top up a tank before winter storage? To occlude water. And that's all.

If you want to treat your 50 year old car to old gas, go for it.


GMc

If it smells bad you can be sure it is bad.

Dave

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The brave don’t live forever
The cautious don’t live at all

And what WWII tanks ran on diesel? Certainly not
German tanks. American tanks all ran on Gasoline. Not sure about British tanks

I also do not add stabil to any gas in a can or in any gas powered tool. It runs fine and gets the job done. The grass gets cut. What more should I expect from it?

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I would never join any club, that would have me as a member. - G. Marx

I wouldn’t want to use any gas over a year old, but I wouldn’t dump it. Just start the car and top off the tank. Make sure your filters are new and drive on.

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1978 MGB
When diagnosing issues related to running and stalling, always check to see if you have gas in the tank first.

A few years ago, I let the gas (probably E10) sit in my snowblower over the summer. IIRC, I had used Sta-bil too. I took it for repair and the carb had to be cleaned out and rebuilt. That was a $90 lesson.
Now, in equipment like that, I drain the tank and run it dry before storage. The MG only gets ethanol free gas.

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I'd rather wear out than rust out.

"If everyone is thinking alike, then somebody isn't thinking." General George Smith Patton

In my experience, gasoline will last much longer if the climate around it is stable. I have had cars sit in the garage for 2 years with the same gas in them. Started right up. Seen cars that have sat outside for the 4 seasons that the gas has gone sour much quicker, if I recall, in 1 to 2 years.

I was kicking myself for not draining my lawnmowers when I last used them back in October.

Turns out everything was perfectly fine. For reference what I didn't drain were a couple of 1970s era Lawn-Boys. Probably the biggest saving grace was that I always shut off the fuel and run the carbs out of gas every time I use them, plus the Lawn Boy brand 2-cycle oil I normally use has stabilizer in it.

I also used up a full gallon of mixed gas from back in the fall this spring and it was fine. New gas cans seal very tightly and seem to keep gas well.

The lawnmowers and gas cans spent all winter in my unheated and uninsualted garage(it gets cold out there, especially when it goes sub-zero outside).

My MG unfortunately hasn't been driven in a little while-hoping that changes soon-although I pumped the tank last year when I saw that it was going to be laid up for a little while. With that said, I tend to think that concerns about gas going bad are a bit overblown. I have always been diligent about using stabilizer, which does help(I use Sta-Bil marine, which is much more economical than the standard kind). The only time I've had a gas related issue in my MG, I was driving the car a lot and filling up often, and attribute it to buying at a station that didn't sell a lot of premium...

43 years of sitting in a warm garage……

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Law of Logical Argument - Anything is possible if you don't know what you are talking about.

"Anyone with an intense emotional interest in a subject loses the ability to observe it objectively: You selectively perceive events. You ignore data and facts that disagree with your main philosophy. Even your memory works to fool you, as you selectively retain what you believe in, and subtly mask any memories that might conflict."

Lloyd, if that gas is from 1981 it probably has no ethanol. Must still be good!

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Guido Perrone
1979 MGB "Penelope"