How long can gasoline last in a tank

[oil pan 4]

Originally Posted by Old Mechanic

I drain gas after 3 months and put it in the wifes car.

regards
Mech

That is what I plan to do with my generator and its 8 gallon fuel tank. Because if all goes well it will almost certainly never be ran.
So I will install a dump valve on the fuel line and drain gas from the generator into other small machines that see a lot more run time than the generator. Then just top off the generator.

[Ryland]

Changing the gas on motorcycles that have sat a single winter is a common fix, E10 has a shorter shelf life then 100% gasoline and the higher the grade of gas the longer the shelf life tends to be.

Two things happen over time, the volatile part of the gasoline evaporates leaving less flammable varnish and the gas tank can have water condense in it.

A sealed gas can or gas tank will keep gas much longer, so some lawn mowers will have their gas go bad much quicker then others, depending on how everything is vented.

The Chevy Volt starts it's engine for a number of reasons, including burning off gasoline that is in the fuel lines and injectors, but it also needs to keep the internals of the engine coated in oil.
The fuel system on the Volt is designed to keep the gas fresh for years.

In a "normal" gas can, it's often said that gas has a 6 month shelf life, at that point it will still burn in many engines, but that it starts to loose it's octane rating.

[XYZ]

Originally Posted by Ryland

A sealed gas can or gas tank will keep gas much longer, so some lawn mowers will have their gas go bad much quicker then others, depending on how everything is vented.

I have several 5 gal cans of e10 gas, some of which is at least a year old. I use it for my lawn equipment. As long as the can is well sealed, it works fine and I haven't noticed any difference, no matter how old the gas is. One of my vehicles is garaged in storage for about 8 months of the year. Again, it always runs well with no difference when I put it back on the road.

I don't believe in fuel stabilizer additives, and I don't use them. However, I do empty out the fuel tank on my snowblower and lawnmower before storing them out of season. I've noticed that storing them with relatively little gas in their vented fuel tanks tends to evaporate and leave gunk deposits in fuel tanks and carburetors.

[Ryland]

Originally Posted by XYZ

I have several 5 gal cans of e10 gas, some of which is at least a year old. I use it for my lawn equipment. As long as the can is well sealed, it works fine and I haven't noticed any difference, no matter how old the gas is.

Gasoline does seem to last longer in a gas can or car gas tank then it does in a lawn mower or motorcycle gas tank, I suspect part of it is the more stable temperature and better seals.
I have "fixed" countless motorcycles, mopeds, lawn mowers and snow blowers by replacing the "year old" gas.

In motorcycle owners manuals they always say to store the motorcycle with either a full or an empty gas tank, never half way or worse 1/8 full because you have a lot of surface area for moisture to condense and a lot of air space for vapors to form and escape.

A friend of mine who owns a motorcycle shop once said that fuel injection will kill his business because the sealed fuel systems nearly eliminate fuel related issues.

[XYZ]

Originally Posted by Ryland

Gasoline does seem to last longer in a gas can or car gas tank then it does in a lawn mower or motorcycle gas tank, I suspect part of it is the more stable temperature and better seals.

You understand what I said about a vented fuel tank.

I have "fixed" countless motorcycles, mopeds, lawn mowers and snow blowers by replacing the "year old" gas.

I have fixed many lawnmowers, blowers, etc. with gunked-up carb reservoirs. The residue left from evaporated gas is like varnish. Once there is crud is in the carb, the engine ain't gonna run.

In motorcycle owners manuals they always say to store the motorcycle with either a full or an empty gas tank, never half way or worse 1/8 full because you have a lot of surface area for moisture to condense and a lot of air space for vapors to form and escape.

The same thing applies to all gas powered engines.

A friend of mine who owns a motorcycle shop once said that fuel injection will kill his business because the sealed fuel systems nearly eliminate fuel related issues.

He understands that. I do, and you do, too.

[redpoint5]

I've had cars start and run on 10 year old gas, and failed to start a lawn mower with gas that sat over winter. The lawn mower breaths too easily and absorbs water.

I suspect that fuel with higher concentrations of ethanol will absorb water out of the atmosphere more readily and spoil the fuel. Perhaps the opposite of this is true, as the solution to water in a the fuel tank calls for using alcohol to absorb it.

[cowmeat]

We have a back-up generator (for hurricane season) that sits unused for years at a time. A couple of ounces of Stabil in the tank keeps the ethanol from gumming up in the carb, and I fire it up every six months or so and let it run until it warms up. I also use Stabil in my pressure washer and mowers, and I've never had an issue yet with the carbs fouling.
I've considered putting it in the Festiva since I only get gas every couple of weeks, but that might be overkill!

[oil pan 4]

Just be safe and run ethanol free gas if you can get it.

[XYZ]

Originally Posted by oil pan 4

Just be safe and run ethanol free gas if you can get it.

I don't believe it's the ethanol (exclusively?) that is causing foul deposits. Gasoline has other additives in it, even if it doesn't contain alcohol.

[Ryland]

Originally Posted by XYZ

I don't believe it's the ethanol (exclusively?) that is causing foul deposits. Gasoline has other additives in it, even if it doesn't contain alcohol.

There is a strong pattern tho.
Talk to anyone at a motorcycle shop or small engine repair shop and ask about ethanol and shelf life of gasoline.