I tried Opti-2 in my LawnBoy Dura-Force this season, and believe it to be the best. Perhaps Amsoil is just as good. I used Amsoil in all my hand-held Stihl machines for the past couple of seasons - better than Stihl oil (no exhuast buildup, starts easier and runs better).
The only place I've found Opti-2 2 cycle oil is at Jagor Equipment. I ordered it online. No dealers in this area stock the item. I chose to mix 75:1, not 100:1. When I started using Amsoil 100:1, I thought engines seem to run a bit "loose." They didn't sound solid. I know, hard to explain, but running 75:1, the engines sound better.
Do a bit of math on the costs. The pouches are very costly, compared to the 1 gallon bottle (or even the quart bottle). By using the large bottles, one can measure out the mix desired, eg. 75:1. The pouches are intended for specific quantities of gasoline. Yes, one can vary the amount of gasoline used with the amount of oil in a pouch, but varying the amount of oil in a particular gas container is easiest.
Now that my supply of Amsoil is nearly depleted, next season I intend to run Opti-2 in both the LB and all Stihl engines, at 75:1.
If anybody has another source of Opti-2 online, please post. Thanks.