I run Stewart oil in my Stewart engine. In a pinch because my last bottle broke and spilled, I had to run an alternate oil. I used 5-20 Mobile 1.
As soon as I got home, ordered a case of Stewart oil. In ordering I confirmed with Howard Stewart two things:
- The Mobile 1 is compatible with his oil, so a simple drain/refill was all that was required.
- He confirmed his oil had Anti FOaming agents, something also touted by Briggs/Amsoil.