As as been posted on earlier threads on this board, the new "low emission" 'CJ' diesel oils have reduced the ZDDP.
The earlier 'CI' diesel oils have higher concentrations of ZDDP. The ZDDP, and anti-wear additive, is mainly useful in areas of boundry lubrication such as on cams with regular type lifters (as opposed to roller lifters). Most of the rest of the engine, such as the jouirnal rod bearings and pistons, do not require the ZDDP.
