Patent ID: 7972496

Claim:
A manufacturing method of a process oil, comprising: deasphalting a vacuum residual oil of a crude oil to obtain a deasphalted oil; and solvent-extracting the deasphalted oil to obtain an extract, wherein the extract obtained and a lubricant base oil having a polycyclic aromatics (PCA) content of less than 3 mass % are mixed to obtain a mixed oil, the mixed oil being provided as the process oil and having the following properties: (a) a polycyclic aromatics (PCA) content of less than 3 mass %; (i) a kinematic viscosity (100° C.) of 30 to 80 mm 2 /s; (j) an aniline point of 90° C. or lower; (k) a flash point of 240° C. or higher; (l) a benzo(a)pyrene content of 1 mass ppm or less; (m) a specified aromatic compound content of 10 mass ppm or lower; and (n) a polar substance content of 10 to 30 mass %.