NLGI Classification of Grease Consistency
Consistency is the resistance of a grease to deformation (similar to the viscosity of oils). NLGI (National Lubricating Grease Institute) divides greases into nine NLGI consistency classes: 000, 00, 0, 1, 2, 3, 4, 5, 6. Very soft grease (grades 000 – 0) is called “fluid grease” and is used, for example, in centralized lubrication systems of specialized trucks. All other lubrication points in vehicles are normally lubricated with NLGI greases of classes 2 or 3.
Numerical scale for grease classification is based on ASTM D217 standard for measurement of penetration (penetration) of special cone into the grease at 25 °C. In order of increasing consistency (hardness):
NLGI Grease Consistency Classes
| NLGI Class |
Penetration level (0,1 mm) | Appearance of grease at room temperature |
| 000 | 445-475 | very liquid |
| 00 | 400-430 | liquid |
| 0 | 355-385 | semi-liquid |
| 1 | 310-340 | very soft |
| 2 | 265-295 | soft |
| 3 | 220-250 | semi-solid |
| 4 | 175-205 | hard |
| 5 | 130-160 | very hard |
| 6 | 85-115 | superhard |
Some suppliers use the NLGI 1.5 grease consistency designation. This means that the grease is between NLGI 1 and 2.і 2.
Note
For complete and up-to-date information on the NLGI grease consistency classification, please refer to the website: www.nlgi.org.