I dont know what is going on with my trimmers but i recently started running opti 2 mix oil which i was running stihl befor. But i have notice that my edger has been dieing when i let it idle and then my string trimmer started doing the same thing. Anyway today i used my hedge trimmer for the first time this week it was running great and it had stihl mix from last week well i ran it out of gas so i filled it up with the new gas and it started doing the same thing. I can not figure this out but it suddenly dawned on me this after noon that it might be the new oil mix. I know alot of guys are running this stuff with no problem. I dont know what the deal is. Its not bad gas because all my mowers are on the fresh fuel from the same pump and are running fine, and yes i am sure that i have the right ratio mixed atleast according to the bottle.