Lubricating oil additive for flexible fuel engine and composition

The invention discloses a lubricating oil additive for a flexible fuel engine. The lubricating oil additive is prepared from the following raw materials: high-base-number calcium alkyl salicylate, high-base-number calcium sulfurized alkyl phenolate, a 4-pyridine ethylene-propylene polymer, alkyl diphenylamine, 2, 6-di-tert-butyl-alpha-dimethylamino-p-cresol and nano BNNs boron nitride. The invention discloses a lubricating oil composition for a flexible fuel engine, which comprises the lubricating oil additive for the flexible fuel engine, an emulsifier and base oil. The key problems that a dispersing agent, a friction reducing agent and an anti-wear agent in engine oil are hydrolyzed, molecular structures are damaged and a lubricating function is lost due to the fact that a large amount of water is generated in the working combustion process of the flexible fuel engine can be solved, and meanwhile the technical problem that low-temperature cold start of the flexible fuel engine is difficult due to water is s