Seafoam was made for pulling a vacuum hose and running half a bottle into the car letting it site for a few hors and then running in the rest of the bottle. 100 miles latter you need an oil change and check / clean your plugs. B12 is about the same thing but cheaper sold where seafoam is not sold.
It’s good to thin out the oil to help with a flush right before you an oil change or to toss in the gas tank but would never put it in the tank at the mix it calls for.
I do use rubbing alcohol right before a cold chill to help with gas lines freezing up. It’s the same as isopropyl alcohol but in a cheaper package.
But rubbing alcohol is watered down. I don't like the idea of adding water to my tank. Although it would be expensive, I bet Everclear or Virginia Lightning (VA Lightning is nothing more than legally produced moonshine) dumped in the tank would clean it out.
BG 44 K was what we used. In the old days of pintle type fuel injectors it would make a difference. The newer designs are not as susceptible to getting gummed up.
In eastern Virginia everything is 10% alcohol, to reduce emisssions. They had to drain the tanks when the stations changed over to keep the alcohol from dissolving all the accumulated goop in the station's tanks.
I havent used any additive after the change over to 10% alcohol here.