Depends on the vehicle. B100 and Veg oil are not the same thing.
B100 is processed to make the glycerin drop out. I run B100 in normal, common rail, modern diesels every day.
Veg oil is way thicker, it would kill a common rail set up. But I run it in this old Mercedes engine straight without a problem, it just has to be heated when it's cold out. I don't bother heating it, I just mix it with diesel or gas to thin it.