If you look on the following site, it tells you all. http://journeytoforever.org/biodiesel_aleksnew.html or you can look here www.ravenfamily.org/andyg/vegoil.htm or you can buy Biodiesel from here http://www.bioroute.co.uk/. No doubt there are many other sites that can help you if you search the net. You can use straight veg oil blended with diesel too. Still have to pay duty so no saving apart from the planet!