NLGI grade

The NLGI grade (National Lubricating Grease Institute) describes the consistency of a grease – its stiffness or deformability. The scale runs from 000 (semi-fluid) to 6 (block-like) and is determined by worked penetration in a standardized cone test: the deeper the cone sinks, the softer the grease and the lower the grade. NLGI 2 is the usual standard for rolling bearings, balancing adhesion, pumpability and mechanical stability. Softer grades 0–1 suit centralized systems and low temperatures; grade 3 suits vertical shafts and elevated temperatures. The grade says nothing about base oil viscosity, thickener or additives – never select grease by consistency alone.