There is something one can add to get castor oil to mix with gasoline, but I forget what it is at the moment.
Klotz Benol is supposed to mix well with gasoline or methanol. They added some ingredient to it.
http://www.klotzlube.com/techsheet.asp?ID=2

But mineral oil has a unique trait where it can moderate the combustion process when the engine is running. That might be a key factor when mixing up kerosene, gasoline and oil to run in a model compression engine. But castor oil does not do this. Many years ago the Drone engines used 75% ether and 25% mineral oil for their fuel. The mineral oil moderated the combustion process otherwise all that ether would quickly damage a engine.

So one would have to mix up a batch with Klotz Benol to see what happens. Or use the secret ingredient that lets castor oil mix with gasoline and kerosene.