I've never used Ring Free before, but I don't have a Yamaha outboard either. I do have a Yamaha jet-ski that I've run Sea-Foam through, as well as my truck, bass boat, duck boat, pontoon boat, and four-wheeler. I use it for everything! It's awesome!!! With all of my toys, I have very little time to do any carburetor cleaning or rebuilds, so I do all I can to keep my fuel system clean, and Sea-Foam does the trick! I've been using that stuff for ten years!