Correlating Wear with the Lubricant Properties of Heavy-Duty Diesel Engine Oils

Wear volumes were correlated with the lubricant properties of 11 used, heavy duty engine oil samples.The most important oil property in predicting wear volume is Total Acid Number, TAN.Here, the TAN value may be indicating ZDDP in its oxidised form and unable to participate in corrosive-abrasive wear.Low wear also correlates with mean soot particle size/circularity, which further suggests the abrasive aspect of this mechanism.Finally, low wear correlates with high calcium concentration in the fresh oil.This suggests a new wear reduction mechanism in which calcium from the detergent replenishes the iron within the ZDDP antiwear film.