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  • Long term fuel storage

    How long is too long to store avgas? You pump fresh 100LL from a known source (FBO, etc) into a steel (or poly) 55 gallon drum and close it tight. The drum sits outside, either in the sun, or in the shade (could be a cold building) in such a way that water can not infiltrate through the bungs. The drum remains sealed, you do not open it. You do not add any additives, extenders, or isopropyl alcohol.
    How long would you let that gas sit before you would not use it for your aircraft? Would that change by the engine you operate in your aircraft? Some engines were designed for 80-87. Some have mods for Mo-gas. There may be other factors to consider.
    Would that change by the quantity stored; 5 gallon steel jerry jug, 5 gallon poly jug, 15-30 gallon poly drums, etc?
    Just curious,
    ARR

  • #2
    I don't know much on the subject, but I think avgas is much better than mogas in this respect. It has a much different formulation as I understand it. A P-38 that was rescued from beneath the Greenland ice where it got buried during WWII, still had some avgas in the tanks when located. The gas was more than 50 years old. When tested in a lab, the gas still met mil spec! There was a book written about it if you are interested. Read about it here.
    http://en.wikipedia.org/wiki/Glacier_Girl

    Today's avgas might be different than what was used in WWII. To be sure, you need ask a chemist that knows.

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    • #3
      Back in the mid1980s I was working in Seward and somebody dug up an old 55 gallon drum of military Purple 130-140 octane Av-Gas.
      It was still good and I used it in my Harley low rider.

      Around Seward people were often digging up full ammo cans and all sorts of WWII left over items that the Army had buried. I still have a couple cans of 30 cal AP with old cloth belts.

      I have used av-gas that I have stored in my own 55 gallon drums for a year. My drums are stored under cover in the coolest part of the property.
      When I store my lawn mower for the winter or my snow blower for the summer, I fill the tanks with 100 LL and run it for a couple minutes. I never have varnish build up in my carbs that way.
      The local Chain Saw guy told me to stop doing that with my Stihl chain saws. It said that av-gas is too hot for 2-cycle engines.

      It has been my experience that long term storage in plastic jerry jugs is not a good idea. Somehow or another junk and gunk gets into the gas.

      I really miss the old 5 gallon Blazo cans.
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      • #4
        I am not sure of the correct answer but I would not worry much about running 2-3 year old av-gas if it was stored properly. Even longer if it was getting cold and that was all I could get. If it will go boom the prop will turn. Now leaving fuel in a carb for that long is bound to cause some problems. There should be some smart fuel guy along for the straight poop.
        DENNY

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        • #5
          I have no idea as to how well it would hold, but if it is marginal, maybe consider mixing it 50-50 or some other ratio with good, new fuel until the old stuff is used up? Just a thought to keep from potentially wasting some good money in "not quite good enough" fuel.

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          • #6
            I'd trust a steel drum more than a plastic drum but I've burned 6-7 year old regular car gas from plastic drums in high performance Snowgos and had no ill effects. We think nothing of parking planes in the fall with half tanks and flying them the next spring and that's with vented tanks. With a good condition steel drum that kept it's seal I wouldn't hesitate to burn 5 year old avgas and probably wouldn't mind 10 year old gas. It's all a crapshoot but if the fuel level is where it's supposed to be and the gas hasn't evaporated off what's to hurt it? A partial drum would cause more concern, mostly because it would be harder to trust. Good question, though. I don't expect there's one good answer. Like the old saying goes, mogas is better than no gas. The same would be true for "mature" gas.

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            • #7
              This guy seems to know what he is talking about<>
              http://generalaviationnews.com/2011/...fely-stored-2/

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              • #8
                Interesting discussion so far, thanks folks. I have a 0-320 160hp engine, which appears to be high compression, or higher than the 150hp version. In my case, and this is just doing research, not talking to a pro, it looks like I need to run 100LL. For higher compression engines like mine, or the 0-360, it seems that octane, or anti knock, might be critical. That would seem to mean I would have less room for error.
                It seems to reason, though my reasoning may be flawed, that a tightly closed container would not allow octane to be lost, or at least very fast. That seems to be supported by the article presented by Monguse. That article talks about the lead dropping out, but if so, then could you pump from the bottom, or shake the drum?
                Certainly it makes sense to get and use good quality fuel. If a guy had some lying around as described, it seems as if it is likely ok to use it for a while at least. I'd also think that if a plane had a low compression engine designed for 80-87, that you could lose a lot and still not be hurt. To me that translates to pretty old gas.
                As for a fuel to be too hot for an engine, I am not sure I understand. If an engine is low compression, or designed for lower octane, and you use higher octane fuel, my understanding is the extra octane is simply not used. It adds no more power to the engine than low octane gas. I've used avgas for years in 2 stroke engines; snowmobile, chainsaws, outboards, with the only side effect possibly being I need to clean plugs more often. But that is not scientific, or objective, simply subjective.
                Any more comments?
                ARR

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                • #9
                  FYI, auto fuel STCs are applicable to 0-320/160hp and 0-360 Lycoming engines. Many operators would testify that they run better on unleaded gas and pump supreme has a sufficient octane rating. I know guys who run car gas and others who blend car gas with avgas. I use avgas and haven't had lead fouling in TCM or Lycomings. I've used mogas when that's all that was available to me and it's worked fine. I'd rather have some car gas in the tanks than to run on fumes wondering if I'll make it to the next stop. The same would apply to old avgas. If in doubt add the car gas or old avgas to only one tank. Use the avgas tank for takeoff and switch to the car gas or old avgas for cruise.

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                  • #10
                    If you have questions about its use ability don't run it or you will not feel comfortable , if on the other hand you want to run it that much and still don't trust it 100% run one tank empty put it in there and only use it while at alt. enroute. Then on some aircraft you are required to be on both or left tank etc. for t/0 , only a little food for thought. When in doubt run it in you atv etc..
                    Now on the other hand if you are trying to plan how to stash fuel at a remote cabin and use it the next yr. for instance, 30 gal blue. Barrels are fine over the winter, just watch for water when filling the plane , condensation . Good luck.

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                    • #11
                      Certainly stashing fuel comes to mind. Then again, on another note, years back, I was w/ a guy and we ran low on fuel. We stopped at a cabin, guy he knew, and found some gas in a barrel. It was iffy, not horrible, but a tad bit suspect. We added it to one wing to dilute it, and headed home safely.
                      I just opened a steel drum w/ avgas from a few years back, and lo and behold, it was sweating in the top just a bit. Not bad, just a bit. I do filter both coming and going, and rarely ever put my pump all the way to the bottom of a drum. Old habit.
                      It would be interesting to talk to a gas "guru" who can talk to octane, anti knock properties, low and high levels, etc. A lot of what we know is from experience (often valuable) but is subjective. With that said, I am certainly enjoying the feedback,
                      ARR

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                      • #12
                        Originally posted by Ak River Rat View Post
                        Certainly stashing fuel comes to mind. Then again, on another note, years back, I was w/ a guy and we ran low on fuel. We stopped at a cabin, guy he knew, and found some gas in a barrel. It was iffy, not horrible, but a tad bit suspect. We added it to one wing to dilute it, and headed home safely.
                        I just opened a steel drum w/ avgas from a few years back, and lo and behold, it was sweating in the top just a bit. Not bad, just a bit. I do filter both coming and going, and rarely ever put my pump all the way to the bottom of a drum. Old habit.
                        It would be interesting to talk to a gas "guru" who can talk to octane, anti knock properties, low and high levels, etc. A lot of what we know is from experience (often valuable) but is subjective. With that said, I am certainly enjoying the feedback,
                        ARR
                        The guys up at the polaris race shop in Wisconsin here put 3-4 lbs. of nitrogen in their race fuel drums when they are not using them to help hold the octane level.

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                        • #13
                          Well I would be more concerned with how the fuel was stored and in what than the age of the fuel. Avgas will store a lot longer that you would think if its done properly, the question is what is the proper way to store it and what is the best conditions to store fuel, I am most concerned with contamination, Ie water, and well theft, lets face it, fuel is expensive these days.

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                          • #14
                            The purple stuff was 115/145 and ran well in my 396 Nova. BTW, nice article you did on fueling in the August Fly-Low publication. The spruce covered area sounds like where I fuel across the street.....

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