What is NLGI grade?

NLGI Grade is a widely used classification for lubricating greases. It was established by the National Lubricating Grease Institute. Greases are classified in one of nine grades based on their consistency. NLGI Grades 000 to 1 are used in application requiring low viscous friction. Grades 0, 1 and 2 are used in highly loaded gearing. Grades 1 through 4 are often used in rolling contact bearings where grade 2 is the most common. Grease Consistency — Lower numbers are softer and flow better, while higher numbers are firmer, tend to stay in place, and are a good choice when leakage is a concern.