SAE Viscosity Grade for Motor Oils

SAE viscosity classification groups oils according to their flow characteristics at low and high operating temperatures. For example, in "15W-40", the "W" indicates winter performance at low temperatures, while "40" indicates the viscosity value at high operating temperature.

Motor oils are divided into two main categories: single-grade oils such as SAE 30 and SAE 40, and multi-grade oils such as 5W-30 and 10W-40.