I was winterizing my 90 hp. 1983 Merc. Ob. In my boats built in gas tank I poured a 16 oz. can of SeaFoam a quart of (5w30) Penzoil, 12 gal. of unleaded, a quart of Penzoil outboard motor oil and another 12 Gal. of unleaded. Then I took the boat to the lake and went for a spin around the lake...