It is for 4 mix and stihl say not for use in 2 mix, which is why I have super not ultra as my first saw, the ms180 is a 2 mix.I always thought Ultra was the stuff developed to run in 4-mix products to combat carbon buildup on the valves? Either way, I quit using it in my Kombi and it seems to be just fine with whatever I dump in it mixed at 50-1.
The super seems fine, iirc it matches the ultra for the jaso specs but it's only semi synthetic. I got XP when I got my 365 and now I've learnt that is highly rated by Steve's nephew I'd stick with it, and it is fully synthetic like the ultra. I'm not expert but suspect the jaso spec doesn't reveal why the full synthetic oils do have an advantage.
For the time being I run 50:50 Stihl super: XP at 40:1 to use the super up. Then it'll be neat XP at 40;1