European engines are designed to use FAI fuel. I have used as much as 10% nitro with no problem in the ST V-60. I have used 20% oil both straight castor and castor / synthetic blend with good results. It is a very light weight engine with power on par with a K&B .61 in my experience. The ST V-60 is still highly revered in CL Stunt circles and many parts are available. You could probably find a lot of info from those stunt guys if you need more.