fuel shelf life

Discussion in 'Boats, Motors, Trailers and Towing Rigs Forum' started by top fuel, Feb 8, 2018.

  1. top fuel

    top fuel New Member

    How long will mixed gas last? Can I add stable to extend shelf life?
  2. gungadin

    gungadin Well-Known Member

    If you are running non ethanol fuel, add a good quality marine stabiliser. The fuel does lose some of its octane rating, but with the preservative, it will last over 5-6 months. Most marine fuel (marked ) is 91 octane rating while most outboards run fine on 87 octane fuel (check your manual). In the past I mix 50/50 ne4w mixed fuel with the old fuel and have encountered no problems. Use a good fuel/ water separating filter and drain off the water after each trip, until you find no more water or have gone through a tank or so. With ethanol fuel, you have a very good chance of having water accumulate, so you may have to drain the filters more often. I usually leave my portable tanks about 1/2 full over the winter, before topping up before the first trip of the year. I once left a tank of fuel for two years and all the fuel had evaporated, leaving a very slimy mess on the bottom, of 2 stroke oil and stabiliser.
  3. top fuel

    top fuel New Member

    Any suggestions on where to find a good fuel/water separator

    CIVANO Well-Known Member

  5. gungadin

    gungadin Well-Known Member

    I don't know where you live, but any marine supply store will have Racor filters, they are a good product with a see through bowl that allows you to see if there is any water in your fuel. You can also get them with a metal bowl, a bit stronger perhaps, but you cannot see the water and so you must open the drain each time you head out. There are also a lot less expensive filters on the market that have no bowl at all, but of course you need to remove the filter element to empty it. A lot more inconvenient, but doable. You are running a two stroke, so unless it is fuel injected or is a low horsepower model up to maybe 25hp, a 20 micron filter is fine. For a fuel injected engine or a very low hp engine I would use a 10 micron filter.
  6. casper5280

    casper5280 Well-Known Member

    One thing to remember the clear plastic bowl is for outboards only. You need the metal bowl for I/O motors. Should you ever have a fire your insurance would be void.
  7. top fuel

    top fuel New Member

    Thanks it's a 50 Hp yamaha with oil injection removed
  8. gungadin

    gungadin Well-Known Member

  9. Wild Bill

    Wild Bill Active Member

    Yeah nothing wrong with this type of filter, used them for years.
  10. Rain City

    Rain City Well-Known Member

    If you pour fuel on a shelf it couldn't last more than a couple minutes. It's science. :)

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