I use the Quicksilver cocktail. Quickleen and Quickcare, 1 oz each per 6 gallons. Im very fortunate to have a station that sells non-ethanol fuel a couple miles from the house. First few times I went out my Opti smoked like crazy. After about a tank with the mix it settled down and now it runs very smooth.No smoke, smooth idle, and runs like a scalded dog. I believe its also recommended as an ethanol treatment. Look over on BBC under The Mercury motors section for more details.Last edited by RazorCat on September 9th, 2013, 8:15 pm, edited 1 time in total.