[Tcoat]

Originally Posted by mdm

And cleaners/detergents are a separate issue, they are about preventing/removing carbon buildup in the intake system, especially on intake valves (unless the engine uses direct injection, then of course fuel detergents can't clean the intake valves because the valves do not come into contact with fuel).

Cleaning capability is per se indepent of octane rating, though some brands put more cleaners in their premium (high octane) fuels.

Cleaners/detergents also have no effect on HP, at least not directly. I mean, if there were no or insufficient cleaners, gradually carbon buildup would interfere with engine operation and reduce HP, but that's not the effect the OP has in mind, I suppose.

All gasoline is supposed to contain cleaners, there are standards for that. But - at least in the US - some gas brands set their own higher standards: "Top Tier" gas.

The use of the words "regular" and "premium" don't help the misconceptions either! Premium implies that it is somehow better overall which is not the case.