Abstract: The effects of three overbased calcium sulfonate detergents on the friction performance of manual transmission oil were studied. The friction coefficient, wear spot and scar were analyzed and evaluated by HFRR high frequency reciprocating rig, SRV wear machine, MPR micropitting rig and Automax synchronous bench machine. The results showed that the three kinds of high base calcium sulfonate all had anti-friction and anti-wear effects. When the dosage (w) was 1%, the detergent C with the highest calcium content and alkali value had the best anti-friction and anti-wear effects, the friction coefficient, the diameter of wear scar and the change rate of MPR roller width of oil were the smallest, and the axial wear of Automax synchronous ring was the lowest.

Key words: overbased calcium sulfonate, detergent, lubricating oil, anti-friction and anti-wear