Is there any possibility of serious engine damage when low octane number gasoline is used?

Yes, using low octane gasoline in an engine designed for higher octane fuel can lead to serious engine damage over time. This is primarily due to knocking or pinging, where fuel ignites prematurely in the combustion chamber, causing increased pressure and potential damage to components like pistons and valves. Persistent knocking can lead to reduced performance, efficiency, and ultimately, catastrophic engine failure if not addressed. It's essential to use the fuel grade recommended by the manufacturer to avoid these risks.