I've never used any fuel system additives and have never had any fuel system problems despite six months per year of storage for the last ten years.

Use a "Top Tier Gasoline" (google it if you don't understand what it means). All gasolines have detergent additives to keep the fuel system clean, but Top Tier brands like Chevron with Techron meet a new tough OEM developed standard for keeping fuel systems clean.

Duke