Uniteasy is more than unit conversion

Engine Oil Viscosity Classifications - SAE J300 a


SAE
Viscosity
Grade
Low temperature (°C) High temperature (100 °C)
Cold Cranking viscosity
(cP, max) b
Pumping viscosity
(cP, max, no yield stress) c
Min viscosity d(cSt) Max viscosity d(cSt) High shear viscosity(cP), at
150°C and 106s-2, mine
0W 6200 at - 35 60,000 at - 40 3.8 - -
5W 6600 at - 30 60,000 at - 35 3.8 - -
10W 7000 at - 25 60,000 at - 30 4.1 - -
15W 7000 at - 20 60,000 at - 25 5.6 - -
20W 9500 at - 15 60,000 at - 20 5.6 - -
25W 13000 at - 10 60,000 at - 15 9.3 - -
20 - - 5.6 < 9.3 2.6
30 - - 9.3 < 12.5 2.9
40 - - 12.5 < 16.3 2.9f
40 - - 12.5 < 16.3 3.7g
50 - - 16.3 < 21.9 3.7
60 - - 21.9 < 26.1 3.7
  • a All values are critical specifications defined by ASTM D 3244
  • b ASTM D 5293
  • c ASTM D 4684. Note that the presence of any yield stress detectable by this method constitues a failure regardless of viscosity
  • d ASTM D 445
  • e ASTM D4683, CEC L-36-A-90 (ASTM D4741) or D5481
  • f 0W-40, 5W-40, 10W-40 grades
  • g 15W-40, 20W-40, 25W-40 and 40 grades

Multigrade oils are used for year round service in automotive engines except some 2 stroke diesel engines. Oils of this type generally require the use of VI improvers in conjunction with mineral or synthetic basestocks.

HT/HS viscosities are measured at 150°C under shear stresses similar to engine bearings. The HT/HS performance indicates temporary stability of VI improvers used to formulating multigrade engine oils. For instance, according to the SAE classification, an oil must achieve 3.7 cp of HT/HS value or higher in order to be classified as 15W-40 viscosity grade. The thinner the oil the lower the number.

At low temperature, the high shear rate viscosity is measured by ASTM D 5293, a multitemperature cold cranking simulator(CCS) method. The low temperature, low shear rate viscosity is measured by ASTM D 4684. Both methods simulate working conditions of engine starting up and engine oil pumpability respectively at low temperatures.

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