In order to make the Baotou Benz diesel engine parts engine lubricating oil is not easily oxidized in use, long service period, prevent the acid of the oil (containing the original and generated a few in use) metal corrosion, so in this kind of oil are added antioxidant. Baotou North Mercedes spare parts diesel engine bearings are mostly copper lead alloy, it can be high load but not corrosion-resistant, therefore, the number of adding antioxidants to diesel oil is more. The main antioxygen and anti-corrosion agents used now are two alkyl (aryl) two zinc thiophosphate. It can interrupt the oxidation of lubricating oil, the lubricating oil is not easy to oxidize viscous resin and asphaltene and acidic substances; at the same time, it is with Baotou North Benz accessories bearing metal reaction generates a layer of protective film, this layer of protective film is dark, can protect the metal from corrosion, also can reduce the wear of metal. Therefore, the use of diesel engine (gasoline engine) lubricating oil lubricated bearings in dark color is the normal phenomenon, is the performance of the performance of the additive, do not scrape it.