|NLGI Number||ASTM worked (60 strokes)
penetration at 25 °C
tenths of a millimetre
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.