Often when comparing greases NLGI numbers will be mentioned. What are these NLGI numbers?

In simple terms the NLGI is a measure of the relative hardness of a grease used for lubrication as determined by the National Lubricating Grease Institute (NLGI) in the USA. These standard classifications are widely used. The NLGI is a not-for-profit trade association that as part of its remit it publishes industry standards for greases.

Below is a useful table explaining NLGI numbers
(Reference: Rudnick, Leslie R. (2005). Synthetics, Mineral Oils, and Bio-Based Lubricants: Chemistry and Technology (Chemical Industries). CRC. p. 468. ISBN 1-57444-723-8).

NLGI consistency numbers
NLGI number ASTM worked (60 strokes)
penetration at 25 °C
tenths of a millimetre
Appearance Consistency food analog
000 445-475 fluid cooking oil
00 400-430 semi-fluid apple sauce
0 355-385 very soft brown mustard
1 310-340 soft tomato paste
2 265-295 “normal” grease peanut butter
3 220-250 firm vegetable shortening
4 175-205 very firm frozen yogurt
5 130-160 hard smooth pate
6 85-115 very hard cheddar cheese

Common greases are in the range 1 through 3. Those with a NLGI No. of 000 to 1 are used in low viscosity applications. 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. For more information see Wikipedia.

For any queries regarding any requirements you might have for greases or lubricants, we are available to assist.


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