I have some 3? year old gasoline stored in a red plastic gasoline container. It is safe to use in my automobile?
There’s no way I’d do it. Even with fuel stabilizer, two years would be pushing it.
If you insist, at least spread it over several full tanks.
Does it still look and smell like normal gasoline?
Maybe, maybe not. Gasoline eventually does break down and depending on the particular blend and the storage conditions, its hard to say how long the shelf life is. Three years is probably too long. The safe thing to do would probably be to put it in a lawnmower or something else that it will be easy to get it out of if it doesn’t work.
I suppose if its only a gallon or two, you can probably dilute it in your tank with good gas, but I’d say its not worth it.
Sure. Add no more than one gallon to a nearly full tank. You should not have any problems. Use the remainder in the same fashion.
Pour a small amount into a clear glass. What does it look and smell like? If it is dark tan / orange in color and smells like old paint thinner, DO NOT use it, even in small amounts. If it’s pretty clear and smells like gasoline, you can safely use it by mixing it into fresh gas…
I am going to go along with Steve.
Caddy is not wrong as there is some, if remote possibility of a problem, I think I would mix it in. I think I would add no more than a half gallon per full tank of fresh gas.
While I would not bother to put it in the car, except for the bother to safely disposing of it.
only if the container is pretty airtight and keeps it fresh
With that kind of age on it I would not use it at all.
Some gas will go stale in 6 months and not even be useable.
I would look at it this way. Any degradation process has a rate. As soon as the gas is blended and loaded on the truck, maybe before, it is degrading. The concentration of whatever bad stuff is in degraded gas increases with time, maybe faster in some containers than others, maybe faster at higher temps. You have a lot of evaporation, some oxidation and maybe a little polymerization. That is all I can think of off the top of my head since I am not an organic chemist.
With this assumption, and some others like the reaction rates are linear over time, if you mix a gallon of four year-old gasoline with seven gallons of relatively fresh stuff, you have gasoline that is the equivalent of 6 months old. If you spread it out over several tanks of gas in your car, it becomes insignificant. I would make sure that there is nothing solid in it before dumping it in. Keep in mind that I took organic chemistry a long time ago so I am dangerous.
If the suggestions of mixing small amounts in with your gas make you nervous, then then mix small amounts in with your lawnmower gas. I’ve done both many times without problem.
I agree with Caddyman - if it’s separated, contains solids, or smells like old paint thinner, then find another use for it.
Joe
only if the container is pretty airtight and keeps it fresh
While an open container can cause problems because the lighter weight hydrocarbons will evaporate first, there is still a very real problem even in a totally sealed container.
The smaller (lighter) hydrocarbons will polymerize into larger heavier chains. The stabilizer products slow that effect.
With this assumption, and some others like the reaction rates are linear over time,
As the reactions continue they will typically increase in speed for a while they will slow down as the mix changes and only larger less reactive chains remain.
If you want to see just how good it is pour a spoonful or two onto the pavement, followed by dropping a match on it.
There’s a good chance it may not even burn and if so why even put it in your car.
Don’t do it. Gasoline is a mixture of components that evaporate at different rates constantly changing the characteristics (basic) of the blend. You can smell truly stale gasoline, but in a vented can for years? No way.
There’s a good chance it may not even burn and if so why even put it in your car.
Well I doubt if you will find it will not burn 
In any case, you will find that diesel, that has more power per unit of fuel than gas, will put a lit match out if you put it in the diesel.
In any case it will mix with the existing gas and if you don’t, you still need to dispose of it safely.
NOt worth taking a chance. You can’t be sure of the mixture on the fuel anymore, so use it in a lawnmower or othr small engine. LEE
Actually I have seen several instances where gas was very, very close to not igniting at all.
One involved old gas in a car that had been sitting for several years and the other was a car that was towed in after a guy had filled the tank.
The latter (daily driven vehicle) had odd looking gasoline that we could never determine exactly what it was. It was clean, free of impurities, and it would take approx. 15-20 seconds to ignite it, and even then it was very slow burning. No explosiveness to it at all.
The former was just old gas and exhibited the same symptoms.
There is always the possibility that the old gas may do nothing more than dramatically lower the octane rating. In the motorcycle racing days of the 1920s guys used to carry a 1 ounce vial of oil and if they won would discreetly drop it in the gas tank while they did a victory lap circle (on the other side of the track of course).
This would cover up that high octane av gas they were cheating with.