Viscosity Grades for Industrial Lubricants

Each refinery usually produces a limited number (5 to 12) of base stocks, since each base stock requires that there be economically sufficient precursors in the front-end feed and, as well, in the feed to the final fractionation after all processing is complete. In addition, the refinery tries to adjust production rates for individual base stocks to meet their demand. Today, base stocks are classified by their viscosity in square millimeters per second (mm2/s) (or centis-tokes) measured at 40°C and usually employ the International Organization for Standardization (ISO) system for industrial lubricants (ASTM D2422), with a range of 2 to 3200 cSt. Twenty viscosity grades and their ranges are provided in Table 1,6.7 

Grade Identification Midpoint, cSt at 40°C Viscosity Limits, cSt at 40°C Minimum-Maximum American SUS Grades (Range) 

Source ASTM, ASTM D2422. With permission. 

The Society for Automotive Engineers (SAE) has developed a viscosity classification system for finished (i.e., not just the base stock) engine lubricants that defines viscosity ranges as well as low temperature properties. The 2004 SAE J300 grades are shown in Table 1.7.9 

SAE Viscosity Grade Viscosity (cP) at Temperature (°Q, Maximum Viscosity, mm2/sec (cSt) at 100°C  

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Table 8.1 Viscosity grades for industrial lubricants, ISO Standard 3448...

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