This might be an old post, but I’m new to the forum. I work in the marine industry and Highly recommend Marine Formula Sta-bil. It needs to be used everyday and can be used for storage. It has water removers along with corrosion inhibitors and cleaners. I have a 1965 Starcraft with a 100 hp merc on in and it works great.
Seafoam makes alot of claims but for the most part it is just a kerosene based cleaner. If you want the best fuel system cleaner then buy some Chevron Techron it’s the best fuel system cleaner on the market. Sta-bil is the best Stabilizer, and if you have a big ol diesel then you gotta go with power service cetane boost.