I don't want to start any war on oil types. I just want to let you friends in the US know that 10-12% oil is the norm in Europe for many fliers. The reason is, we have different types of oil available here in Europe than you guys in the US. Why, I don't know. Aerosave oil, for instance, has viscosity index higher than that of castor oil. I myself run my engines (currently Saito FA-125a and Laser 300v and 240v) on 10% Aerosave and 5% nitro. By the way, Laser engines say 10% good quality oils is fine for Laser engines.