Patent ID: 7388122

Claim:
A method to produce a dewaxed oil, comprising: dissolving a dewaxing aid together with a wax-containing hydrocarbon oil into a dewaxing solvent, separating-out wax by chilling, wherein the chilling rate during the chilling is 30° C./minute or higher, and removing the separated-out wax with the liquid/solid separation method; wherein the dewaxing aid comprises a mixture of: (A) at least one polyalkyl(meth)acrylate having alkyl groups of 10 to 30 carbon atoms, and (B) at least one polyalkyl(meth)acrylate having alkyl groups of 10 to 30 carbon atoms which is different from component (A), wherein: the mass ratio of component (A)/component (B) is from 3/97 to 97/3, and the dewaxing aid satisfies the conditions of formulas (1) and (2) below at the exothermic heat initiation temperature as measured by a differential scanning calorimeter at the chilling rate of 30 °C/minute: −4.00° C.+ Ta≦ta≦ −1.0° C.+ Ta (1) Ta≦tb ≦4.00° C.+ Ta (2) where: (Ta) is the exothermic heat initiation temperature of the wax-containing hydrocarbon oil without the addition of said dewaxing aid, (ta) is the exothermic heat initiation temperature of the wax-containing hydrocarbon oil with the addition of 0.25% by mass of the component (A) to the wax-containing hydrocarbon oil, and (tb) is the exothermic heat initiation temperature of the wax-containing hydrocarbon oil with the addition of 0.25% by mass of the component (B) to the wax-containing hydrocarbon oil.