There is no fuel that is suitable for the YS engines. The only solution would be to box it up and send it to me.
Seriously, I think that you'll find most airplane fuels will be fine in the YS engines. YS recommends 15% - 20% oil, either castor, synthetic or a blend and a nitro content of 15% - 30%. Most airplane fuels fall into those ranges. Personally, I don't use any castor in my fuels because I don't like the burnt residue castor can leave on the motor and the way it gums up inside an engine that isn't used regularly. I use 30% nitro helicopter fuel in my YS engines. Depending on the brand, they have 20% - 23% oil and the engines run super on it. The higher nitro gives a little more power, makes the tuning easier and gives a great idle. I have never had a fuel related issue in my YS's using the 30% (100% synthetic oil) heli fuels.
Hope that helps rather than confuses you.
Paul