Evaluation of lubricating properties of titan truck plus 15W40 oil used in marine diesel engines

The paper presents the results of lubricating properties tests of Titan Truck Plus 15W40 motor oil. Tested oil was used in Caterpillar 3512B high-speed engines, which propelled the tug boat. The lubricating properties parameters were determined for fresh oil and used oil samples. Builder of Caterpillar 3512B engine recommends lubricating oil change after every 1000 hours of operation. Lubricating oil samples were taken from engine oil system after 342 hours of service and after 1024 hours of service, it means just before lubricating oil change. The test results were collected by means of a four-ball extreme pressure tester T-02 according to Polish Norm PN-76/C-04147. The following lubricating properties parameters were determined: weld load Pz, maximum nonseizure load Pn, seizure load Pt and load wear index Ih. Investigations showed that for used oil samples maximum nonseizure load and seizure load increase but weld load and load wear index decrease. These results indicate that used oil has higher boundary layer resistance (better antiwear properties) but worse antiseizure properties, which are determined in hard working conditions of the sliding node elements. In author’s opinion, worsening of the antiseizure properties results of solid impurities presence, which come from lubricating oil deterioration process. To verify that thesis the detail analysis of the tested oils chemical content has been made. Spectrol Q100 spectrometer, which can specify content of 24 chemical elements in the lubricating oils was used for this purpose.