O.M.C Evinrude/Johnson Rotary Motors had their own Rotary Outboard Motor Oil. Not to be confused with the regular Evinrude/Johnson 50:1 Outboard Motor Oil, back in the day, plenty of the Rotary Oil was available. However now there is none available, unless u happen to find someone who has a bunch of it stashed away, which is pretty much impossible. Anyway, What oil, today, will replace the Rotary Oil? Some say use a good Sythetic Oil. Well, I know a guy who did this in his Evinrude Rotary. The motor was fine before. However, after only 1 month of use, he disasembled the motor and it was pretty well shot, so Synthetic Oil is not the answer. What Oil is best for the Rotary O.M.C Motors?