Abstract: A simplified, essentially maintenance-free yet highly efficient distillation tower and method for waste oil rerefining is provided which allows direct vacuum distillation of additive-supplemented waste oils without chemical pretreatment thereof and yields a highly refined intermediate oil suitable for immediate use or final polishing, along with a valuable bottoms fraction usable in greases or asphalts, for example. The tower includes an upright, cylindrical chamber with a tangential waste oil inlet and cooperating internal baffle for creating a whirling oil flow pattern therewithin, along with means for maintaining the proper temperature conditions within the tower for maximizing vaporization and recovery of hydrocarbons from the waste oil while also preventing undesirable decomposition or cracking of the oil.