Is 2 years old gas bad for an engine?

Gasoline typically begins to degrade after about six months but may remain usable for up to a year if stored correctly in a sealed, air-tight container. Beyond a year, gasoline begins to break down chemically, forming gum and varnish deposits that can clog carburetors and fuel injectors. It also loses its potency, making the engine harder to start and less efficient.

Therefore, using 2-year-old gasoline in a combustion engine, even if it contains ethanol, is not advisable and may cause performance issues, damage to fuel system components, starting problems, or engine hesitation and stalling. It's generally recommended to use fresh gasoline and avoid storing fuel for extended periods to ensure optimal engine performance and reliability.