A new kind of friction-reducing and repairing additive containing nano-scale copper and rare earth compounds were prepared by means of synthesis and compounding methods. The performance of the said additive was investigated by engine bench test, and was compared to the performance of similar domestic and imported additives. The deterioration of lube oils containing additives over different time intervals was studied by means of plasma spectrometry and mass spectrometry, and the effect of additive package on engine power was also studied. Test results have revealed that the synthetic additive package can provide good anti-wear performance to the tribo-pairs. In particular, after 300 hour application of the said additive package the connection rod shaft and copper sleeve showed "zero wear" to achieve the in situ dynamic repairing of tribo-pairs. Application of the said synthetic additive can effectively improve the engine power performance and extend the engine service life.