Use conventional 2 cycle oil and mix it at 2.5 ounces per gallon for 50:1 mix for a Puch. If you filled your tank already, put 2.5 oz of oil in it and ride.
Easiest way is to pump 1/2 gallon of gas at a time when your out riding because its only a 1 gallon tank and you don't want it totally full. Buy some mini ?4oz? 2 cycle bottles of oil at walmart and a quart of oil. Pour 2.5 ounces of oil in the small bottles after you use the original stuff in the bottle. They are a dollar n change at walmart. Buy a cheap measuring cup to get it consistent every time. Put the bottle in your pocket or pack and if you need gas, pump 1/2 gallon gas and pour in half bottle- 1.25 oz of oil. That's what I've always done and it's only a little prepwork in the garage but makes a gas stop so much quicker.