As far as diluting the gasoline, the 87-89-93 sticker is the minimum octane rating of whatever comes out of the hose. Half of it could rat piss. 10% of it could be corn mash. Whatever it is the RON+MON / 2 is what the sticker says.

I never understood why oil companies insist on adding additional cleaners to gas. Gasoline is a great solvent. None of the 100k mile motors I've taken apart have had the "coral reef" looking buildup on the backs of the valves. You know what will clean that carbon off? Normal gasoline and a toothbrush. How the hell is carbon getting there? Combustion doesn't happen in the intake port. Isn't that from oil leak down from the valve stem seals? Wouldn't you be better off not driving around a beat motor that burns oil?