I have always ran either sta bil or seafoam in my 1989 mercury 175 since the day I bought my champion. My carbs had never been off for cleaning till last month. I took my boat in because I had a needle and seat leaking. They corrected the needle and seat problem and installed boyesen reeds per my request. I have friends that had to get their carbs worked on yearly and they still won't run additive. I'm a believer!