All my YS engines run the best on CP 30% Heli......thin viscosity 30%nitro 22% oil.
I have tried mixing my own stuff and it never runs as good as the CP stuff.
I have used regular Klotz and the thin vis Klotz but the engines are pretty finicky about their diet.....1/2 oz of acetone per gallon helps the idle considerably.
I used to use polypropylene oxide (1/2 oz/gallon) but it's too hard to get around here.
Morgan has discovered something that makes them run better.