RE: Fuel
you don't have enough detail, it's completely dependent on the application of the engine. in all my heli's and most of my sport planes i use 100% synthetic but in my prop jets and delta wings that are built to haul butt and are turning up 20 thousand Plus RPM i use a 20% castor/80% synthetic blend. at those RPM a bubble in the fuel line can cause a lean enough run to gald a piston so the castor is a necessity.
kc