fuel shelf life

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