If fuel sits in a vehicle for a long time without being used, it can eventually degrade, and in some cases, that can create problems for the car.
In a fully sealed, airtight environment, fuel can remain stable for a long time. But once it moves through the distribution chain and ends up in a vehicle's fuel tank, it is no longer completely isolated from air, moisture, and temperature changes.
At that point, oxidation and contamination become real concerns. Over time, fuel can begin to separate, break down, or lose some of its original properties.
Read more: https://www.msn.com/en-us/autos/news/gasoline-has-an-expiry-why-leaving-5-gallons-in-your-tank-is-killing-your-pistons/ar-AA1Xz6Pt?ocid=XMMO&apiversion=v2&domshim=1&noservercache=1&noservertelemetry=1&batchservertelemetry=1&renderwebcomponents=1&wcseo=1