| 摘要 |
PURPOSE:To obtain a gear oil composition, having extreme-pressure properties and abrasion resistance comparable to those of a conventional gear oil using a sulfur-phosphorus-based extreme-pressure additive (SP-based gear oil) and excellent in thermal and oxidation stabilities by adding a specific compound and a zinc dialkyl dithiophosphate together to a base oil for a mineral oil-based lubricant. CONSTITUTION:This gear oil composition is obtained by blending a base oil for a mineral oil-based lubricating oil with (A) an alkali metallic borate hydrate in an amount of 0.1-1.5wt.% expressed in terms of boron, (B) 0.1-10wt.% zinc dialkyl dithiophosphate expressed by the formula (R1 to R4 are 1-20C primary or secondary alkyl) (preferably having a 3-15C primary alkyl group) and (C) 5-30wt.% compound selected from monoesters, diesters, polyol esters, alkyl carbonates, polyoxyethylene alkyl ethers and polyoxyethylene alkyl phenyl ethers. Furthermore, a dispersion of potassium borate or sodium borate obtained by using an ashless type dispersing agent such as a neutral calcium sulfonate is preferred as the component (A). |
