viscous neutral oil

viscous neutral oil

[′vis·kəs ¦nü·trəl ′ȯil]
(materials)
The bottoms from reducing, by distillation, of a petroleum neutral oil fraction; such oils are frequently blended with bright stock to make finished oils of various viscosities.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.