Hey Foamy, check out weston and model technics for their aero engine fuels in the UK (both have websites, weston do mail order, MT sell via Ripmax outlets) and take on board some of the other suggestions on this thread. Car engines are completely different to aero engines (revs and operating conditions being just two considerations). 15-20% oil for planes is the norm, that's just the way it is. Consider also that when a nitro car engine dies, the car stops, when a nitro plan engine stops the plane (potentially) crashes to earth (or hits a person in the head), so some different sensitivities being played out here.

Regards,
Andy