It's more likely to see it listed as a ratio such as 50:1. Good move buying Stihl, it is great oil and a great product. Mix as directed, shake, use. Try to mix as little as needed. I do store and use 2 stroke mix with no problems but fresh is best. The Stihl dealer I worked for hung a note on each repaired item saying use fuel no more than 45 days old. A little extreme but so many fuel issues with small engines. 2 stroke equipment will store with less problems because the diaphragm fuel pump type carbs do not have "bowl" that is open to the atmosphere like 4 stroke equipment.