Methods and devices for economically producing a purified biodiesel product from feedstocks. Some embodiments of the methods comprise using at least one of a crude feedstock pretreatment process and a free fatty acid refining process prior to transesterification and the formation of crude biodiesel and glycerin. The crude biodiesel is then subjected to at least one biodiesel refining process which, in conjunction with feedstock pretreatment and free fatty acid refining produces a purified biodiesel product that meets multiple commercial specifications. A wide variety of feedstocks may be used to make biodiesel that otherwise would not meet the same commercial specifications, including corn oil, used cooking oil, poultry fats, fatty acid distillates, pennycress oil, and algal oils. The combination of feedstock refining and biodiesel refining processes is necessary to reduce problems associated with feedstocks having waxes, high free fatty acid levels, unacceptable color, high unsaponifiables levels, and high sulfur levels.