Fuel adatives?

Do any of you use any fuel additives on a regular basis? and if you do what kind?  My boat sits at a pier all summer and can't help but think all the hot days and cool nights has to be creating condensation in the tank.  Although i'd assume all engine makes would be interested. In my case i'm running a Evinrude E-tec

StaBil Marine in every tank. Always premium, ethanol free when available but I go through gas quickly enough I'm not terribly worried about it. Probably not the best way to do it, but I've never had any gas-related problems.

I use alcohol free fuel in my small engines. Along with that I use SeaFoam on a regular basis. This had kept all my motors running well and smooth. Haven’t used Stabil for seasonal storage now that I treat with SeaFoam year round. 

Always use the premium recreational gas (non ethanol) from Kwik Trip. Sea foam once a year, usually mid summer. Stabil when I winterize the boat and I always winterize on a full tank.

I've used StaBil for years and more recently StaBil 360 in all power equipment and outboards. NEVER any fuel related problems. I also take a bottle with when traveling to Canada where the possibility of getting some stale fuel at a dock exists. Not saying anything disparaging about Sea Foam. I just stick with what works for me.

Sea Foam in every tank of fuel for everything but the trucks.

Since gas is said to break down in a month or so, any gas I don't plan on using within 2 weeks gets Sea Foam added.  In things that I know may sit longer, I use premium (non ethanol) fuel only.  I mistakenly filled up my tiller tank 3 years ago...I just used the last bit of that old fuel last week and it would start on the 2nd pull each time!  I also add Sea Foam to my autos a few times a year to improve gas mileage.  Buying Sea Foam is definitely an extra cost up front, but seems to keep all of my engines working well when I need them.  Good luck.

I run Seafoam through my motors once per season. I also add Stabil 360 Marine with every tank (except when I use the Seafoam). I only use non-ethanol premium gas.