US Patent 7473347 Process to prepare a lubricating base oil

Process to prepare two or more base oil grades, which base oil grades have different kinematic viscositys at 100° C. from a waxy paraffinic Fischer-Tropsch product having a content of non-cyclic iso-paraffins of more than 70 wt % by:(a) obtaining from the waxy paraffinic Fischer-Tropsch product a distillate fraction having a viscosity corresponding to one of the desired base oil products;(b) performing a catalytic dewaxing step using the distillate fraction obtained in step (a) as feed;(c) separating the lower boiling compounds from the dewaxed product obtained in step (b) in order to obtain the desired base oil; and(d) repeating steps (a)–(c) for each base oil.