NLGI grease classification
| NLGI Number | ASTM worked (60 strokes) penetration at 25 °C tenths of a millimetre |
Appearance |
| 000 | 445-475 | fluid |
| 00 | 400-430 | semi-fluid |
| 0 | 355-385 | very soft |
| 1 | 310-340 | soft |
| 2 | 265-295 | "normal" grease |
| 3 | 220-250 | firm |
| 4 | 175-205 | very firm |
| 5 | 130-160 | hard |
| 6 | 85-115 | very hard |
Common greases are in the range 1 through 3.
Those with a NLGI No. of 000 to 1 are used in low viscosity applications.
Examples include enclosed gear drives operating at low speeds and open gearing.
Grades 0, 1 and 2 are used in highly loaded gearing. Grades 1 through 4 are often used in rolling contact bearings.
Greases with a higher number are firmer, tend to stay in place and are a good choice when leakage is a concern.