Fuel additive?

[Billua]

Stabil every tank except once per year I throw in two cans of Sea Foam..

[IDBoating]

As noted in other threads, our local Cenex gasoline does not use ethanol in its premium (91 octane) mix. Lower grades have progressively higher percentages of ethanol. So I use the premium grade in all my marine and offroad vehicles to keep the ethanol - and attendant moisture - out of their fuel systems. The extra octane is wasted on these engines but keeping the ethanol out is important so I don't mind the extra $0.20 per gallon.

On my fuel-injected Mercury 2-stroke V6 engine I added the proper amount of Sta-Bil and Seafoam to every gallon. I also decarboned the engine with an ultra-rich mix of Seafoam in a separate tank once per season due to the increased carbon buildup common to 2-stroke engines. On my fuel-injected PCM 4-stroke engine I intend to do exactly the same except for perhaps less frequent decarboning, based on what I find on the plugs and what a borescope shows me inside the cylinders.

[dom w. forte]

The only bad thing we find here in fla. about the higher octane, is less people use it so it is not as fresh as the 89 or 87, my ski team boat performs better on the 89 and we add a product here called Sentry which mixs with the water and burns off in the fuel , it has done a great job for my boat.

[IDBoating]

The only bad thing we find here in fla. about the higher octane, is less people use it so it is not as fresh as the 89 or 87

That's an excellent point. So far I haven't had any problems. The gas station where I get my fuel is at the entrance to a resort-like area so hopefully they see more premium sales during the summer (boating) season.