Petrochemicals | Measurement of engine oil using a temperature-scanning technique with ViscoQC 300

Flow problems are associated with the engine oil’s viscosity and gelation and will lead to poor lubrication and potential engine failure. As prevention a temperature-scanning technique according to ASTM D5133 was performed with the rotational viscometer ViscoQC 300.

Introduction

The temperature-scanning technique according to ASTM D5133 allows to analyze an oil’s viscosity and gelation properties at low temperatures.

The pumpability of engine oils at low temperatures is important to prevent engine damage after cold temperature starting. The pumpability of oil is limited at a certain point due to either gelation or due to viscosity that is too high. After reaching a certain viscosity the volume of oil being pulled through the pump is lower than what is needed to adequately lubricate the motor. A viscosity of 30,000 mPa·s or 40,000 mPa·s is known to cause pumpability problems depending on the engine manufacturer.

When the oil gels an air void will be created within the oil in the sump. The oil is too thick to fill the void, and thus the pump just pulls in air. Oil gelation in engines will result in excess wear as friction increases or, in extreme cases, a stop-right-now failure. Gelation of oil is marked by an increase in viscosity over the normal exponential increase of viscosity with decreasing temperature. It is attributed to a process of nucleation and crystallization of components of the engine oil and the formation of a structure. 

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