Bright Stock refers to lube base oils of high viscosity produced by atmospheric distillation and vacuum distillation, then extracting and dewaxing solvents from residual oils. And finally hydro finishing. Bright stock is used to make lubricating oils of the desired viscosity by mixing with lubricating oils of low viscosity (used for adjusting the degree of viscosity). stock is usually blended in lubricating oils of high viscosity such as gear oil, marine diesel engine oil, and cylinder oil. The word ‘Bright Stock’ comes from the method of producing bright colored oils by blending naphtha with dark-colored Cylinder Stock, leaving it through to winter, extracting wax ingredients from it, and then distilling to remove the floating naphtha solution. Bright stock is not only blending material for lubricating oils, but also a product itself. For instance, Stock made from an Iran crude oil is quenching oils with excellent performance.
| CHARACTERISTICS | UNITS | RESULT | TEST METHOD |
| Appearance | — | Clear and bright | Visual |
| Color | — | 3 | ASTM D1500 |
| Density | Kg/m³ | 910 | ASTM D1298 |
| Kin. Viscosity@ 40°C | cSt | 490 | ASTM D445 |
| Kin. Viscosity@ 100°C | cSt | 32 | ASTM D445 |
| Viscosity Index | — | 95 | ASTM D2270 |
| Flash Point | °C | 315 | ASTM D92 |
| Pour Point | °C | -6 | ASTM D97 |