Why not use what SeaDoo recommends? SeaDoo prohibits the use of TCW oils in all of their motors. I can only speak from experience and of all the Seadoo 2 strokes I've rebuilt going back to the late 80s, I'd say 90% of them had the blue or green TCW oil in them. Many people say it's fine but I completely disagree based on my experience. SeaDoo recommends an API oil, mineral oil non-synthetic for yours, and put a decal right at the oil cap explaining this.