Contrary to how high octane gas is marketed, it only has benefit for engines designed to burn it. High compression engines need a slower burning fuel so it will not pre ignite, Higher Octane rated gasolines burn slower. Pre ignition ping will destroy an engine so it is important to run proper fuel in the engine. However, Over kill on octane simply will do no good, sometimes it can even burn black.
The gasoline we buy these days does leave deposits on the intake valves and on piston heads and heads etc. It is wise to run some Seafoam or Marvel Myster Oil in the tank once in a while. MMO has been around for many years and does work very well. Seafoam is also an excellent product.