If you are buying gas every 2 to 3 weeks, I wouldn't worry about it. I have International truck thats been sitting for 5 yrs that I fire up a occationally that has Seafoam in it all the time. I dilute 1 ounce to the gallon.
One of the uses of seafoam is as fuel stabilizer. I leave seafoam treated fuel in my small engines for a full season while in storage with no problems.
