What is the oil to gas mix ratio for an echo pb251 leaf blower?

50 to 1 gas to oil or 50:1...Just make sure that you purchase oil that is rated 50:1. Most places that sell oil will sell 6-packs of 2.6 OZ. containers to mix with 1 gallon of gas each. I personally use the Napa oil (Napa is Valvoline oil) or if I am passing my Stihl dealer I'll grab it there...BUT...Napa delivers it to my door :)