After reading that mixing a fraction of diesel or kerosene is a decent way to bypass a fuel heating system, I became curious and did a bit of research. This has revealed that these fluids are not perfectly miscible, and that as they separate when the tank is cold, the WVO may solidify. This could lead to some problems with cold starts, and eventually the problems you would encounter running pure WVO without a heater. More here:

http://journeytoforever.org/biodiesel_svo.html

-Ravi