This SAE-ASTM Symposium entitled "The Relationship Between Engine Oil Viscosity and Engine Performance"—Part II (SAE SP 419-ASTM STP 621-S1) was presented at the SAE Fuels and Lubricants Meeting in Tulsa, Oklahama, June 6—9, 1977, Part I (SAE SP 416 - ASTM STP 621) was presented earlier at the 1977 SAE International Automotive Engineering Congress and Exposition held in Detroit, Michigan, February 28—March 4, 1977.