I always use 93 ethanol free with Husqvarna oil. Just bought 41 gallons in Dothan Al for 2.89 a gallon. I have not put many hours on it since new. I just checked and I have 10 days warranty left. Will be taking it in tomorrow. I have a 181se I bought new in 87 and never a minutes trouble out of it. Still using it. Have a 55 and a 350 too. $800 saw --they better fix it. I've tried to tune the surge out of the saw to no avail. Had to depress a 3" piece of 1/4" tubing with a small screw driver inserted through the tube to tune. I like to run them a hair rich.