Seafoam states on the can that it helps stabilize fuel, along with other things. So, why use Sta-Bil? Just put Seafoam in by itself if it also stabilizes fuel.

The Sta Bil is for when you let your boat sit for sometime. Does nothing but stabilize the fuel but is needed when your storing for the winter. Seafoam cleans, and improves idle, thru top end' and start up.
Two different products that do two diffetent things. Seafoam Does work though and you can tell the difference first time you use it. Sta-Bil stabilizes the gas only and keeps it from breaking down. Use your boat alot no need.Gas does not have time to break down before being used.

Seafoam does everything that Sta-Bil does so no need. Seafoam all the way.

I use Marine Stabil with every tank of gas but every 2 months or so i put in a can of Seafoam with 10 gallons of gas to clean everything up. Seafoam is a little more expensive to use in every gallon compared to Stabil.
Stabil- $7 can treat up to 80 gal
Seafoam-$10 can treat up to 25 gal.

Im not spending $10 every 25 gal. so i use stabil regularly and seafoam as a clean up every so often.

Incorrect. Seafoam cleans. Stabil stabilizes and neutralizes much of the bad effect of ethanol. Use them together.

That may be true but it says "Fuel Stabilizer" on the front of the Sea Foam can as one of the main things it does.

I add sta-bil each time I add gas. And, add ring free each time I add gas to prevent carbon build-up.

Ring free is expensive but it only takes a tablespoon to 10 gallons as a carbon preventative so overall it's cheap to use.

SeaFoam should give commission to the forum because I just bought some per this conversation. One quick question though, like BigDave above, I use Marine Sta-Bil and Yamalube Ring-Free with each tank, is it ok to also throw SeaFoam in the mix everyonce in a while? That seems like a lot of additives. Should I leave Ring-Free out when I do the SeaFoam or just chunk it all in there?

Truth be known Ring-Free is a decarbonizer too. Prolly don't need both, if your using Ring-Free or Merc's de-carbonizer regularly it may be over-kill to also use Seafoam unless the engine is "Really Carboned up". I wished I would have bought stock a couple of years ago no tellin what it's worth now.

Just the Seafoam and Sta-bil together will do the job.