When is gasoline considered old?

[cegarbage]

I fill up my car with gas about once a month. Since one month is 3 weeks longer than my old cars, I normally work the tank way down to get rid of all the old stuff. Is this necessary? Does that car have the ability to use the old stuff first when mixed with a new tank of gas?

[cwstnsko]

If you are filling once a month, I'd say you have nothing to worry about. Gas does get old, but it generally takes longer than a month and the Energi models have a special fuel system to account for how long we might go between fuel-ups. It's something like 18 months before the car will run the engine to burn up the old fuel before it starts causing problems.

[murphy]

It is recommended that, if you expect the fuel to be in the tank up to the 18 month limit, a stabilizer such as StaBil be added to the tank.  It's available at Lowe's. 

 

The Energi has a sealed fuel system.  When the open fuel door button is pressed there is a delay before the door opens to allow pressure equalization.

 

I last bought gas in June 2014 and still have about 1/3 of a tank left.  My engine usually only runs in the winter.

 

If gas is being put into the tank on a monthly basis there is no chance of stale gas.

[shaggy314]

I've gone 4+ months on a tank. Your car also keeps track of the time and will actually start using the gas to burn it off when it gets 'too old'.

 

Gas gets stale due to air and water getting to it. Since we have a pressurized system, it is much less subject to it.

 

32k miles, lifetime average is now 100.3 MPGe.

Edited September 2, 2015 at 08:13 PM by shaggy314