I could be wrong on this, but;
the difference in octane only signifies how much 'anti-knock' the gasoline has in it. In otherwords; the higher the octane the harder it is to ignite and therefore can be compressed to a higher pressure within the compression chamber. Higher pressure means more power per volume of gasoline/air. Of course it also means more heat, friction, wear, etc.
So, unless the engine is specifically designed for higher compression and actually is a higher compression engine, higher octane will not be needed. No increase in power or efficiency (milleage) results by using higher octane gasoline.
The oposite is also true. Put low octane gasoline in an engine designed for higher compression (BMW I think) and you will get pre-ignition (knocking sound). That sound is the lower octane gasoline igniting BEFORE the cyclinder reaches the top of its rotation. As the compression in the cyclinder reaches the flash point of the lower octane gasoline it ignites as the cyclinder is still coming up. This causes holes in the cyclinder, valves to melt, and rings to seize.
Please real experts chime in. This was from an aviation class 30 years ago, and at that stored in a fading memory card.