If its semi or full synthetic then the usual 50/1 mix should be used, if its not, or its cheap unbranded stuff, personally i wouldnt use it!
Just to confuse the issue(!) Stihl say in their handbooks 50/1 for Stihl oil, for other Quality two stroke oils use 25/1 ratio. Probably easier to buy Stihl oil!
All of our machines are Stihl apart from the mowers, I've been forced to use Husqvarna oil for about the last eight years because the nearest dealer that stocks Stihl oil is 70 miles away. They still work, fingers crossed!