The use of the radioactive ring technique to study variables affecting railroad diesel engine wear was first reported by the Southern Pacific Transportation Company and Standard Oil Company of California in 1961. Researchers from the same companies undertook new investigations in 1969 and 1970 using a current generation turbocharged locomotive. As in the previous program, operation was carried out in a stationary installation with the power generated absorbed by auxiliary air-cooled grids.New testing procedures and counting equipment were employed. Radioactive chromium was counted simultaneously with the measurement of irradiated iron particles in the oil.New and used lubricants with variations in alkalinity value were evaluated using distillate fuels with sulfur contents ranging from 0-1%. Two ring metallurgy combinations were evaluated.