Practical Sailor tested gas add. a number of years ago (have lost the article)) and found that it was useless. I keep my gas (have both a 2 and 4 stroke motors) as "fresh" as poss. and only use the non alcohol prem. gas. and have had no problems. (I put a half gal. into my car to flush the hose then fill my gas can) Has anyone found any real tests, not product statements, that they could share?