Here's why:
* Gasoline shelf life: Gasoline can typically last for 3-6 months in a sealed container, and even longer if stored properly in a cool, dry place. One year is outside that recommended range, but it's not necessarily a guarantee of problems.
* Ethanol content: Modern gasoline contains ethanol, which attracts moisture and can lead to phase separation over time. This can affect performance, but the rate of deterioration is relatively slow.
* Other factors: A rough-running engine could be caused by various issues, including:
* Spark plugs: Worn or fouled spark plugs can cause misfires.
* Fuel filter: A clogged fuel filter can restrict fuel flow.
* Air filter: A dirty air filter can disrupt the air-fuel mixture.
* Fuel injectors: Clogged or faulty fuel injectors can affect fuel delivery.
* Ignition system: Problems with the ignition system, such as a faulty distributor cap or ignition wires, can cause misfires.
Recommendation:
While it's possible that the old gas could be contributing to the rough running, it's best to consider other factors first. Have your car inspected by a mechanic to diagnose the problem properly. They can test the fuel system, check for other potential issues, and determine if replacing the fuel is necessary.
To prevent future problems:
* Use fresh gasoline whenever possible.
* Store gasoline in a cool, dry place in a sealed container.
* Consider using a fuel stabilizer if you need to store gasoline for an extended period.
