We did the real conversion to biodiesel from soybean oil. Add lye and methanol to break the triglyceride into four molecules. This lowers the viscosity and makes it a drop-in replacement for dino diesel. This stuff is good enough that you can use it in your car with no modifications, although I hear it makes your car/truck smell like a hamburger joint. But the big plus is the lack of sulphur, so none of that awful diesel smell.

I suppose you can run straight vegetable oil in a model engine, but it would be tougher. People do it in their diesel trucks/cars but first heat the stuff to 150 degrees F otherwise it clogs the injectors. The biodiesel doesn't have this problem.

As far as mixing goes... I add ether, castor oil, ignition improving peroxide like everyone else does. It's just the kerosene part that's being replaced.