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  1. #1
    Petty Officer 1st Class
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    Default how long before 2 stroke gas is bad?

    How long would you leave gas sit in you tank before you get rid of it? I would think two stroke would last longer!! Any help?

  2. #2
    Petty Officer 1st Class Maddoxsdaddy's Avatar
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    Default Re: how long before 2 stroke gas is bad?

    Typically, no more than 90 days. After that, use it in the weedeater and put new gas in the boat...

  3. #3
    Master Chief Petty Officer
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    Default Re: how long before 2 stroke gas is bad?

    30 days here if there's ethanol in it.
    Love the life you live, live the life you love-Bob Marley


  4. #4
    Admiral
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    Default Re: how long before 2 stroke gas is bad?

    In 40+ years of boating I've never had fuel go bad in 90 days let alone 30 and weve used ethanol here for longer than a decade. In some cases (the worst) it not be great in 90 days, but again, Ive never had a problem.

  5. #5
    Chief Petty Officer
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    Default Re: how long before 2 stroke gas is bad?

    I've never had any go bad over a full winter of storage in an outboard tank. ( I won't use stabil either.) That said, since the intro of 10% alcohol mix fuel, I've been using Seafoam in every tank.

  6. #6
    Petty Officer 1st Class Mike722's Avatar
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    Default Re: how long before 2 stroke gas is bad?

    This is one of those questions that everyone has a differant answer. I have seen engine that will not start on 30 day old gas and others that will on 2 year old gas. The major manufacture of small engines that I use to turn wrenches on advised against using gas over 30 days old. According to their "experts" gas starts to break down at this point. As stated I have seen major problems with valves and push rod because of what I will call old gas.

    At home I take gas that is over 30-60 days old and run it in older engines that will run on bad gas or put it in the car a couple of gallons at a time.

  7. #7
    Master Chief Petty Officer
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    Default Re: how long before 2 stroke gas is bad?

    The question was asked in the form of opinions, I won't use fuel older than 30 or more days unless it's been treated. 30% of Marinas repair business here is due to fuel/ethanol related issues, we have a much bigger problem here due to the humidity and the fact that ethanol attracts moisture thru the tank vents as opposed to the boaters up north. My own boat sat for two months and the injectors were all clogged up from doing that, I won't do it again.
    Love the life you live, live the life you love-Bob Marley


  8. #8
    Petty Officer 3rd Class FlyinGuy1017's Avatar
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    Default Re: how long before 2 stroke gas is bad?

    Your injectors didn't get clogged from bad gas, you got water in your tank. The marina is taking you if they say it's from the ethanol attracting moisture.

    Water and fuel don't mix, they separate. At night, moisture condenses on the walls of the fuel tank and then runs down to the lowest spot (very close to the pickup). In humid climates this can be a nightly process. If you want to keep it clear, fill your tank when you put the boat up. No air on the tank walls = no condensation of water in the tank.

  9. #9
    Petty Officer 1st Class
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    Default Re: how long before 2 stroke gas is bad?

    Thanks for the replys!! I dont know what to do with 30 gal of 2yr old gas that was said to be treated!!! Its alot of gas to get rid of!!

  10. #10
    Master Chief Petty Officer
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    Default Re: how long before 2 stroke gas is bad?

    Quote Originally Posted by FlyinGuy1017 View Post
    Your injectors didn't get clogged from bad gas, you got water in your tank. The marina is taking you if they say it's from the ethanol attracting moisture.

    Water and fuel don't mix, they separate. At night, moisture condenses on the walls of the fuel tank and then runs down to the lowest spot (very close to the pickup). In humid climates this can be a nightly process. If you want to keep it clear, fill your tank when you put the boat up. No air on the tank walls = no condensation of water in the tank.
    they got clogged from the gunk caused by the ethanol converting, it's no scam I cleaned them my self. the ethanol which is alcohol based acts like a varnish remover, it attracts water and cleans all the stuff from inside the tank and fuel lines, if you don't run a 10 micron filter it'll get in there. There has been alot of research done on it here, bottom line is it's causing issues in this climate.
    Love the life you live, live the life you love-Bob Marley


  11. #11
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    Default Re: how long before 2 stroke gas is bad?

    Capt Sam is right about ethanol attracting water. I dont think in two months it would cause that many problems though. I can leave gas in my dirt bike or street bike 6 months and not have issues with it. I started a 72 chevy truck with almost 2 year old gas with no problem. Houston is also pretty humid. Im not debating that the old gas was breaking down or anything like that but 2 months does not sound right. Most likely already had build up in the system for it to give problems after 2 months.

  12. #12
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    Default Re: how long before 2 stroke gas is bad?

    Quote Originally Posted by IVAZ View Post
    Capt Sam is right about ethanol attracting water. I dont think in two months it would cause that many problems though. I can leave gas in my dirt bike or street bike 6 months and not have issues with it. I started a 72 chevy truck with almost 2 year old gas with no problem. Houston is also pretty humid. Im not debating that the old gas was breaking down or anything like that but 2 months does not sound right. Most likely already had build up in the system for it to give problems after 2 months.
    I'm sure there was some build up and maybe some bad fuel, but not likely. I'm on another local forum in which numerous threads have been related to this subject, why it's worse here I'm not sure but it seems to be. Could be a combination of things, I always thought folks were over-reacting until it happened to me and trust me I run my boat 2-3 times a week, every week and am anal on my maintenance. I'll get off the Stabil/Startron wagon but I'm just sharing my personal experiences and they seem to be confirmed by some highly respected individuals in my neck of the woods.
    Love the life you live, live the life you love-Bob Marley


  13. #13
    Captain mthieme's Avatar
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    Default Re: how long before 2 stroke gas is bad?

    I have motors I run only once a year using last year's gas.
    Never had a problem.

    Nothing is so broken that Government can't make it worse.

  14. #14
    Lieutenant Commander bowman316's Avatar
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    Default Re: how long before 2 stroke gas is bad?

    If you vent hole is closed then how would the water get in?
    Everything is selaed up tight when the tank is not in use.
    I am using the standard 6 gallon outboard portable tank.


    I do use that blue bottle for ethonal treatment thou.
    16 ft runabout w/ 70 hp evinrude
    26 ft grampain sailboat

  15. #15
    Moderator Bondo's Avatar
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    Default Re: how long before 2 stroke gas is bad?

    This is one of those questions that everyone has a differant answer.
    Ayuh,.... And here's Mine,.....

    A teaspoonful of gas in a carb will go Bad in a reasonably Short time,... Several months I'd say...
    A 5gal. pail or larger volume can set a year or more....

    I use only 1 Test to see if gas is Usable or Not....
    If it Smells like gas,.. I burn it....
    And,..
    I Never try it get the Last drop of gas from Any vessel,...
    It's usually Water anyways...
    Any Grease is Better,..... Than No Grease at All.......

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