Actually, the Stihl orange bottle is the cheaper stuff. They claim the gray bottle is their “high end” 2 cycle oil.
I used the Stihl gray bottle stuff for a while, since it is one of the easiest to find in my area. I stopped using it when I started seeing a lot of reviews panning it on a couple of chainsaw and Forestry websites.
Switched to the Husqvarna XP+ oil (gray bottle). It’s been working well for me for years now. My only complaint is that I wish their larger bottles had a built-in measuring system for measuring 2.6 ounces accurately. I prefer to mix a gallon at a time, but it just seems wasteful to keep buying those individual 2.6 ounce bottles. (I did order one of those “RatioRite” measuring cups, but it’s not very convenient for me.)