Dale replied ...
Airplane model fuels typically run an incorrect caster/synthetic blend content for nitro cars because they don't rev as high or run as hot and typically have lower nitro content.
I don't disagree with what you said but it almost sounds counterintuitive. By that, I mean ducted fan engines (from .45 to .91 in size) run anywhere between 18K and 23K+ RPM and they seem to "like" around 20% oil content with some of it being synthetic. At least that's been my experience 'cause I've run/flown many gallons of ducted fan fuel!
So, it would seem that fuel with 20% nitro and 13% oil is the all-around choice?
Mike