Well, I can't recommend that you use SVO or WVO, as neither is cleared for on-road use by the EPA.
Both contain glycerine, which doesn't burn cleanly much below 1000*F... it creates toxic gasses when it isn't completely burned.
The point of making bio-diesel from oil is to remove the glycerin from the oil and replace it with methanol, which lowers the viscosity of the fuel and makes it burn more like petro-diesel.
If you google "DIY BioDiesel" you'll find a load of sites devoted to it.
This is the site that I'm going with right now:
Make your own biodiesel: Journey to Forever