You can run it straight, but you need to filter it pretty good, at least 10 microns I would say, but you also need a second tank. You run on diesel till your at full operating temp. then switch over to WVO. When you get where you are going you switch back to diesel till your lines and everything are purged of the oil, then shut-off. You also need a fuel heater for the oil to keep it more fluid if your not in a hot climate, or it can gel in the lines/tank. Also, if your engine isn't hot enough when you switch over you can coke you injectors too. It seems like a hassle to me and I like my bedspace. I don't want to have to run seperate tanks. I would also think the processed oil would burn easier than just the filtered oil. I am also basing this off everything I have been reading, so I don't have any actual experience yet. Though I do work with a guy who runs straight WVO in his 2007 Jetta TDI and said it gets the same mileage and he gets the oil for free, I'm just kinda leary about running straight oil through my pumps and injectors....