I have used Pennzoil air cooled 2 cycle for break in at 40:1 (about 4 gallons) with very good results. There seems to be a shift in the thinking on break in oils. That is, go with synthetic from the start. I did that with a Zenoah G-62 and could tell no difference in the way it ran from a G-62 that had been broken in on Pennzoil air cooled.

Follow the manufacturers recommendations. I fill a 2 gallon plastic jug with 93 octane gasoline and use Amsoil (Dominator) 50:1 mix at 40:1 for my ZDZ80RV. For the rest of them I use Amsoil (Saber Professional) 100:1 mixed at 80:1 and regular gasoline. When I'm taking several planes to the field I take 2 jugs and it doesn't bother me at all. Both usually stay in the trailer anyway.

As important as a good quality oil is the need for good cooling airflow. Put in baffling as required to get the right cooling. I read where people complain about a brand of synthetic oil causing rings to stick when the more likely cause is running the engine too hot. Excess heat sure can stick up the rings and worse.

Ken