I have a Craftsman chainsaw, and the owners manual recommends using the Craftsman Professional Synthetic 2-cycle oil, and using a ratio of 40:1. I pay about $2.50 per bottle for the Craftsman oil, which is the same price as one bottle of Stihl HP Ultra 2-cycle oil. The Stihl oil is also fully synthetic, and it has JASO FB and API TC/TC+ certifications. The Craftsman oil has no certifications. I am wondering if anyone knows anything about the quality of the Craftsman oil? It makes me a little hesitant to use it since it has no certifications, but I like the fact that one bottle of the Craftsman oil gives me a 40:1 ratio when mixed with 1 gallon of gas. One bottle of the Stihl oil gives me a 50:1 ratio when mixed with 1 gallon of gas, so I get a little more oil for the money when i buy the Craftsman oil. However, i know the quality of the Stihl oil is good, but I don't know anything about the Craftsman oil. I have bought some tools in the past from Sears, and they have been complete [censored], so not everything they sell is good quality. Thanks for your input.