APPARENT VISCOSITY USING COLD CRANKING SIMULATOR: ASTM D5293
EXPLANATION
The cold cranking simulator (CCS) apparent viscosity of automotive engine oils correlates with low temperature engine cranking. CCS apparent viscosity is not suitable for predicting low temperature flow to the engine oil pump and oil distribution system. Because the CRC L-49 test is much less precise and standardized than the CCS procedures, CCS apparent viscosity need not accurately predict the engine cranking behavior of an oil in a specific engine. However, the correlation of CCS apparent viscosity with average L-49 engine cranking results is satisfactory.
This test method covers the laboratory determination of apparent viscosity of engine oils at temperatures between -5 and -30° C at shear stresses of approximately 50 000 to 100 000 Pa and shear rates of approximately 10(5) to 10(4)s(-1) and viscosities of approximately 500 to 10 000 mPa•s.
The results are related to engine-cranking characteristics of engine oils.
TEST SUMMARY
An electric motor drives a rotor that is closely fitted inside a stator. The space between the rotor and stator is filled with oil. Test temperature is measured near the stator inner wall and maintained by regulated flow of refrigerated coolant through the stator. The speed of the rotor is calibrated as a function of viscosity. Test oil viscosity is determined from this calibration and the measured rotor speed.
TEST PRECISION
Repeatability: 5.4 % of Mean
Reproducibility: 8.9 % of Mean
