Abstract: The practical properties of the GRT energy-saving oil additive were investigated by long-distance driving testing and short distance technical-economics properties under different conditions in many areas as compared with the same kinds of products from abroad. The results shown that the oil-saving rates of fuel oil and lubricating oil are 5 % and 50% respectively by using GRT energy-saving oil additive, it have reached the level of same kinds of products in 80's from abroad; the cylinder wear of DONGFENG truck and JIEFANG was reduced by 24% and 33% respec-tively; the GRT additive improved obviously the seal property of engine cylinder, not only increasing the cylinder pressure nd the output power of engine to rise the acceleration and cold starting properties, but also improving the combustion situation of the fuel oil to decrease the environmental pollution from the exhaust of truck.