SoCal,
You're right to want to use biodiesel, rather than SVO. As Kwik said. SVO has glycerine in it. Actually veg oil is molecules of glycerine each connecting three hydrocarbons (that's why veg oil's technical name is "triglyceride."). Each of the hydrocarbons is about the same molecular structure as diesel fuel.
Biodiesel is the product of chemically separating these hydrocarbons from the glycerine (called "transesterification") and removing the glycerine. If you burn SVO, you burn the hydrocarbons but not the glycerine, which decomposes into nasty things that do far more harm (especially to rings, pistons and cylinder walls) than the SVO could offset anywhere else.
But if you have a reasonable amount of mechanical aptitude, you don't have to spend the money these biodiesel kits cost. Go to
http://journeytoforever.org/biodiesel_make.html and read their stuff. There are several systems that they have made that you can duplicate. I made my first biodiesel in an old blender and subsequent batches in a 5-gasllon plastic bucket w/ cover, fitted w/ an old drill and paint stirrer as a mixer. Do this before you buy anything, just to be sure you want to be a backyard chemist.
My next unit is going to be a 5-MM plus gal./yr. operation, so you can see that I enjoyed the experience a lot.
Good luck.