is an automotive gear oil classification system developed by the Society of Automotive Engineers (SAE). The SAE 70W, 75W, 80W, and 85W viscosity grades are determined by the maximum cold temperature at which a viscosity of 150,000 cp is attained. For the SAE 90, 140, and 250 grades, minimum and maximum viscosities at 100° C establish the grade designations. Gear oil SAE viscosity grades should not be confused with engine oil SAE viscosity grades.

a.	Centipoise (cp) is the customary absolute viscosity unit and is numerically equal to the corresponding SI unit of millipascal-second (mPa s).
b.	Centistokes (cSt) is the customary kinematic viscosity unit and is numerically equal to the corresponding SI unit of square millimeter per second (mm2 /s).
c.	The precision of ASTM-D-2983 has not been established for determinations made at temperatures below -40°C; consequently, this fact should be realized in any producer-consumer relationship. It is expected that ASTM will shortly undertake work in the range down to -55°C for D-2983.

SAE AXLE AND MANUAL TRANSMISSION GEAR OIL
VISCOSITY CLASSIFICATION

SAE Viscosity Grade	Temperature for Viscosity of 150 000 cpa °C	Viscosity at 100°C cSt b
		Minimum	Maximum
70W	-55c	4.1	—
75W	-40	4.1	—
80W	-26	7.0	—
85W	-12	11.0	—
90	—	13.5	<24.0
140	—	24.0	<41.0
250	—	41.0

Also see SAE engine oil viscosity classification.