| 摘要 |
PURPOSE:To obtain a lubricating oil for a diesel engine which is run under such severe conditions that a low-quality fuel is used at a high output by incorpo rating into a lubricating oil base a boric acid salt, boric acid ester, or boric acid amide of a specific amine compound which is a weakly cationic surfactant. CONSTITUTION:This additive comprises (A) a boric acid salt, boric acid ester, or boric acid amide of an amine compound represented by formula I, II, or III (wherein R<1> to R<4> each is an 8-28C hydrocarbon group; A<1> to A<6> each is a 2-4C alkylene; and (l), (m), (n), (p), (q), and (r) each is 0-20, provided that 1<=(p+q+r)<=20). It is used in combination with a metallic detergent (B). The ingredients (A) and (B) are incorporated into a lubricating oil base together with an ash-free dispersant (C) and an extreme-pressure lubricant (D) in an A/B/C/D ratio of (0.05-10)/(0.5-50/(0.1-10)/(0.01-5), respectively, to obtain a lubricating oil for a diesel engine. The ingredient (A) is obtained by mixing the compound represented by formula (I), (II), or (III) with 0.3-3.0mol of boric acid per mol of N atoms of the compound under stirring. This lubricating oil is prevented from being deteriorated by a low-quality fuel and being contaminated with an acid substance attributable to the fuel, and can have a prolonged life. |
