Running on Old Gas

[Passages]

A friend aquired a boat with 350 gallons of 2 year old gas. My suggestion was to have some extra filters on hand, top it off (holds 400 gal) with fresh 93 octane and run it.

That said, I was wondering if anyone here has had any good experience with these miracle in a bottle gas restorers?

[MikeP]

The problem with old gas is that all the volatiles are gone which makes it extremely poor gas. Filters will take care of any grunge that may be in there but they won't turn it into good gas. The engines may run very poorly or not at all. I had some old gas in a motorcycle tank and the bike wouldn't start or run at all.

I think that will be the biggest issue. I doubt that any additives will do much of anything at this point - none of them can "make" gas out of what is no longer gas. The best thing to do would be what you suggested - add as much fresh gas as possible to the tank - keep in mind that it won't really mix very well with the old gas without some sort of agitation.

You could just add the fresh fuel and see if it will start/run as is. If it will, I wouldn't worry about it at all other than to add fresh fuel as frequently as possible.

If it won't start/run you might consider draining the current fuel in the carb and fuel filters/lines and putting fresh fuel in there - use a hose dropped into a can of new fuel at the fuel filter intake. Then start the engine and warm it up. Then reconnect the fuel tanks and start again and let er run for a while, seeing how she reacts once the old fuel gets there.

If it will continue running with minimal complaint then take her out for a run - don't go too far(!) and keep that tank/can of fresh gas on the boat avialable to be re-connected! If no problems, when you get back add more fresh fuel.

The problem with this is that it MAY run OK on the bad fuel at this point but may NOT start with it when the eng is cold.

If that's the case, then you really don't have much of an option except to either go through this (fresh fuel) process every time you start until enough new fuel has been added to the tanks to eliminate the problem OR you just pump out and get rid of the old gas.

Hopefully you'll be lucky and it will start/run just fine!

[Passages]

Engine started fine and ran smooth at idle and up to 2000 rpm. My buddy is now saying the gas might be 3 years old.

I advised him not to top off the tanks as that old gas might have MTBE. Much more stable that E-10, but I've heard bad stories about mixing the two blends.

Suggested he run the tanks down as low as possible, top off with fresh gas and try to run that down.

Do the experts agree?

[Genesis]

Go get some PRI-G and dump it in there and run it - just don't push it too hard until the fuel is burned up as the octane is probably low.

Run it ALL THE WAY DOWN before refilling; try to burn as much of the old crap out of there before you add any more if there is a risk of MTBE in the fuel and you have Ethanol now, as that is asking for a REALLY ugly mess if the two mix.

I deal with this every spring in my outboard-powered boat and this is my strategy - I also stabilize the fuel before the end of the year - so far, so good.

[Jaxfishgyd]

"Go get some PRI-G"

That IS the gas engines friend!!!!

Brought back my buddy's 33' Bertram from the Abacos in 2001. Gas was AT LEAST 3 years old and from the Bahamas on top of that.

Put in PRI-G (OK, we actually doubled the amount it called for) and the tank was about only 1/2 full, and the motors NEVER missed a beat... We did top off the tank at Spanish Cay.

OH, we were "forced" to spend one night at NIPPERS..... Damn the luck

[krush]

Run it ALL THE WAY DOWN before refilling; try to burn as much of the old crap out of there before you add any more if there is a risk of MTBE in the fuel and you have Ethanol now, as that is asking for a REALLY ugly mess if the two mix.

I call BS. I regularly mix MTBE and Ethanol fuel in my vehicles because some counties are MTBE and others are Ethanol....never had any problems.


This is the 5th opinion, but I say top it off with fresh stuff. Run it some and then keep topping it off every so often. The old gas will burn, it's just that it has lost many of the "goodies".

Hopefully there isn't varnish forming though. Is he going to go through at least 300gallons before the season is over?

Worst case, where is he? I'll fill all my vehicles up with it!