[Ridgemeister]

I see no purpose in those myself.

YMMV.

The only thing I MIGHT consider would be to use Techron a tank or two before an oil change. Or maybe Seafoam if there was an issue that a teardown might otherwise require (tick in the engine or maybe an oil leak that wasn't readily fixable).... just in the hope that it might fix whatever ails the engine.

I don't think there's any substitute for consistent, routine servicing (maintenance) and good operating procedures.

Seafoam??? There is absolutely no proof it does anything. Honda doesn't recommend additives of any kind so why would you?