I use exclusively Omega, mainly because that is the best deal on club purchases, but have been very happy with it.
No problems with my engines. Its castor blend for me.
One of the old guys at the field told me I should use cool power because the caster will gum up the valves in my 4 strokes, he said that was the only thing he used. Not 1/2 hour later he couldn't get his engine started and found the valves had stuck. I had to bite my tounge on that one.