Like K.Kiser, it goes in everything that sits up any length of time (couple weeks or more). Makes a hell of a difference when it is time to start a 4 wheeler, edger, trimmer, mower, etc. which has sat since last season.
Seems to keeps my plugs from fouling in the Merc also. Went through 2 sets in a month then dumped in Seafoam and no issues in past month. Think it cuts the 40:1 mix I'm giving the old gal.