Evaluation of Gear Lubricant Antiscore Properties

The CRC L-42 axle test is used to evaluate the score protection of automotive gear lubricants under conditions of high speed and shock loading. A modification of the CRC L-42 test procedure to increase severity and a screening test to predict axle performance are discussed.

CRC L-42 severity level is increased by using higher speeds and dynamometer loadings during the shock cycles. Under these more severe test conditions, both RGO-110 passing reference oil and API GL-5 quality level lubricants blended from commercially available additive packages gave unacceptable coast side scoring. Scoring could be reduced to satisfactory levels by the addition of appropriate extreme pressure agents to these lubricants. This modified CRC L-42 test procedure serves as a useful tool for evaluating the performance reserve of automotive gear oils.

A screening procedure using the SAE Load Test has been developed which shows good correlation with both the standard and modified CRC L-42 tests. This bench test is both a simple and rapid tool for evaluating experimental gear lubricants for their antiscore properties.