Shelf life of gas before going bad

[RBPowell]

Gas has been sitting in tank for 1 & 1/2 years. 55 gallon tank is about half full. No stabilizer was put in. Seems temperature plays a role on shelf life of gas, so FYI: boat has been sitting under cover, in Florida (hot). Should I drain and put fresh in before running? Are there any additional things I need to do to prevent engine damage?

 

[sloopy]

Re: Shelf life of gas before going bad

about 3 months. less if it is in a hot humid place. Sorry.

 

[waterone1@aol.com]

Re: Shelf life of gas before going bad

Do not, under any circumstances even turn over the engine with that gas in it. Besides draining, flushing and refilling the tank, I would suggest draining the fuel lines and replacing all fuel filters. I hope your carb isn't full of gum from the stale gas sitting in the floatbowl, but that will be evident when you start it and try to get it to idle. Good luck!

 

[BillP]

Re: Shelf life of gas before going bad

It would be best not to take a chance and to drain the tank/carbs and use fresh fuel. However, I live in Florida (56 yrs on the water) and seen many yachts sit for a year or two and have zero problems with fuel sitting that long. "Snowbirds" do it all the time here with gas and diesel and it isn't as bad as some think. If gas only lasted 3-6 mos half the yachts here would be needing carb work annually and that doesn't happen...not even close. It isn't like most treat their fuel either. Call a few yacht brokers in Lauderdale and ask them...they see this all the time. Evidently gas loses octane over time so use hi test if you are topping off and running the old.

 

[Mark42]

Re: Shelf life of gas before going bad

According to Exxon, their gas is fresh for 6 months if stored in a sealed container. I'm sure other major brands do as well. <br /><br />Problems from old gas:<br /><br />- gasolines blended with ethanol can absorb water and separate into a gasoline layer and another water/alcohol layer. So keeping water/moisture out of the tank is important for long term storage. Gas that has separated should be taken to a recycling center.<br /> <br />- Lighter components that assist in starting (like butane) evaporate fist, making cold temp starting harder.<br /><br />- Evaporation from carb bowls leaves a gum behind. This is not really a problem if only the 1 or 1/2 cup of gas in the bowl evaporates because the residue will be negligible. The problem is when fuel continually replaces the evaporating gas, so residue from many gallons of gas build up in the carb. That makes the dark brown sticky stuff you see in gummed up carbs.<br /><br />- Old gas can safely be rejuvenated for use by mixing with new gas in 3:1 newld, if you are worried about using it "as is". Some authorities say mix 5:1, but 3:1 seems to be the accepted ratio. <br /><br />Mark.