I pay $14.00 to $15.00 for 15% nitro 18% blended oil, it's what I run in everything from 1/2A to 1.40, one fuel for everything. The Castor Synthitc thing has been done to death but if anyone thinks a couple of %s of Castor in the mix will save an engine in a lean run then by all means buy fuel with blended oil. Or you can use full synthitc and don't run your engines lean. It's a choice thing and I won't even state how many years I have been running glow engines. That has been dne to death too.