One thing that DarZeelon and I agree on is that a lot of oil is best when running in an engine. Both of us use 25% oil, for myself I use all castor. Maybe it's peace of mind, maybe it extends the life of the engine. But the running in is the most crucial part in determining how good the engine ends up so I don't skimp on it. And SLIGHTLY rich to me is just into a clean 2 stroke, not the couple of hudred revs below peak some recommend. At that setting you might just as well take it out of the box and go fly.