Have a Yanmar 4JH3-TE engine with about 350 hours. I keep both fuel tanks full all the time and generally find a very small amount (5 ml or less) of water in bottom of Racor fuel/water separator at end of the season. Given this, is there any need to use a fuel additive to remove small amounts of water from the fuel? I notice what appears to be rust (reddish brown) on the inside top of each fuel filter element both primary and secondary when I replace them after the course of one season. Probably use about 35 gallons of fuel/season. Presently use biocide, fuel stabilizer and cetane enhancer. Do I need one for water as well?