Hi --- I used Amsoil in my 75 HP Yamaha and had NO PROBLEM at all. Yes - it does not smoke at all which is great upon first startup. Anyway bent the prop shaft last year - now I have a 115 HP Johnson 60o Faststrike --- I use Amsoil in it and again NO PROBLEM. I had the injector system disabled and prefer the 2-cycle mix personally. I am going to put Amsoil lower end lube in it soon. This is MY experience! Sparky