I use penzoil xlf 2 cyl. In gal's--usually bass pro has a sale on this in spring sale--but walmart also carries it. I have been using it for about 3 yrs with no problems.
All is use is Penzoil and i love it plus you can get it for $13 a gallon usually. I would stay away from the Supertech (Walmart ) brand ...my buddy ruined his chainsaw using the Super tech stuff