We just tried to run a race engine on the dyno with 2 year old race gas. The engine ran okay but sounded soft and didn't make good power so we decided to find fresh fuel. The engine picked up 100 hp with new fuel and sounded much crisper. So bad race fuel works, but it doesn't make power. When pump gas goes bad the engine usually won't even run, race fuel is more stable than that but it still degrades.