Can fuel degrade, such as from 98 RON to 95 RON, over time?

Fuel does degrade after a period of time. How fuel is stored will determine how quickly the fuel will degrade. The octane rating will decrease and other additives that are added to enhance the fuel will also degrade. This includes corrosion inhibitors, metal deactivators and any cleaning agents. Fresher fuel will be a better quality. We recommend not using any fuel that has been stored for longer than four months.