NLGI grade is the first spec line every buyer reads, and the one most often misunderstood. The number tells you the consistency of the grease – how stiff it is at 25 °C – measured by cone penetration (ASTM D217). It does not tell you the thickener type, the base oil viscosity or the temperature ceiling. Two NLGI 2 greases can behave completely differently in the field.
What the numbers actually mean
The scale runs from 000 (semi-fluid, like thick oil) to 6 (block grease, nearly solid). Each step roughly halves the penetration depth:
- NLGI 000 – 00: Semi-fluid. Flows under gravity. Used in enclosed gearboxes and centralised systems where the grease must travel through long lines.
- NLGI 0 – 1: Very soft. Pumps easily at low temperature. Common in centralised lubrication for chassis points, and in high-speed bearings where churning losses matter.
- NLGI 2: The industry standard. Soft enough to pump, stiff enough to stay put. Fits roughly 80% of general industrial bearings.
- NLGI 3: Stiffer. Used where vibration or vertical shafts would wash a softer grease out of the raceway, and in pre-packed double-sealed bearings.
A practical selection map
Centralised systems (long pipe runs, multi-point): NLGI 00 – 1. The grease must flow through 10-30 m of line at ambient temperature. A stiff NLGI 2 will leave far-end points starved.
Electric motor bearings (1,800 – 3,600 rpm): NLGI 2 or 3 with a polyurea or lithium thickener. Softer grades churn, overheat and leak past shields.
Slow, heavily loaded plain bearings: NLGI 1 – 2 with high base-oil viscosity. Consistency matters less than film strength here.
Gearboxes (enclosed): NLGI 000 – 00 semi-fluid greases, or switch to gear oil entirely above certain speeds.
Vertical shafts and vibrating screens: NLGI 3. Gravity and vibration are working against you.
Low temperature changes everything
Consistency is measured at 25 °C. At -20 °C the same grease is far stiffer – and may not pump at all. If your equipment winters outdoors, check the low-temperature torque spec, not just the NLGI grade. Our lithium line, for example, stays pumpable to -30 °C in NLGI 1.
What we stock
LLF Grease manufactures the full range: NLGI 000 semi-fluid gearbox greases, NLGI 0/1 centralised-system grades, NLGI 2 workhorse lithium and polyurea, and NLGI 3 for high-vibration positions. Every batch ships with a COA listing the exact penetration value, so you know what arrived – not just what the brochure says.
Not sure which grade your application needs? Send us the bearing type, speed and ambient temperature range – our engineers will recommend a grade and provide free samples for testing.