[MrBonus]

I've used a few ounces at every fill up in all my carbureted cars. I don't know if it makes any difference but certainly hasn't hurt anything to my knowledge.

I've always understood it that ethanol attacks various rubber and seals in the fuel system and Marvel supposedly combats that. Of course, this is the same claim made by every other fuel additive so maybe I'm just being sold a feel good product.