An article on Autospeed got me wondering about this.
I was surprised to read the experts giving answers that were much
shorter than I would have expected.
Depending on whom you ask, gasoline is good for ...
- 6 months - in a sealed container, after which it starts to degrade
- up to 12 months in a sealed container
- "several months" old fuel in your tank risks fuel system problems
- "several weeks" is enough to detect octane degradation, based on dyno testing
Read more from: The Life of Fuel - How long does fuel last in your car's tank?
When I got the Firefly, it had been sitting, the tank nearly full, for seven years
. The engine started normally on the old gasoline, and it ran apparently fine when I test-drove it around the block.
7 year old gas
7 years seemed pretty extreme, though, and I was warned that old gas could gum up the intake valves and make them stick. So I drained the fuel tank to nearly empty, drove straight to a gas station and filled up with fresh gas before driving it home.
OK, so if 7 years is too much, how about four years
? That's how old the gas is in this 1990 Swift GTi:
4 year old gas
... and with a boost, it started right up after sitting in a field for that long.
On the other hand, I have had trouble running a 2-stroke boat motor with fuel that was 2 years old. Maybe it depends on the engine, or the oil mix causes things to go wonky sooner.
Autospeed: The Life of Fuel - How long does fuel last in your car's tank?