Second on Seafoam. Great stuff. Used to it "decarb" both my outboards and regularly in each tank. Made the Johnson 150 run better than ever after the decarb procedure. Works great as a regular additive/stabilizer and I've let fuel sit over winter with the stuff, no problems! When I took my Yamaha 150 VMax for a tune up this spring, mechanic checked the fuel first and said it was still fresh and first rate (it was filled last fall!). Seafoam all the way!