The Development of a Diesel Injector Experiment to Study the Combined Effects of Oxidation and Shear on Lubricating Oil Viscosity

An experimental test rig was needed to apply high rates of shear strain on lubricating oil molecules and study the effects these may have on the degradation of the lubricant. The result was the development of a diesel injection device where the oil could be stressed and cycled effectively. Viscosity measurements were used to determine whether or not the oil had degraded. A change in viscosity in high molecular weight compounds is evidence of chain scission. The results show that cycling a 128 ml volume of oil 12 times has no effect on fresh, unaltered lubricating oils, even at low oxidation times up until 48 hours. However, the results show that heavily degraded lubricating oils near and beyond their usability limit, do exhibit a viscosity loss of up to 0.043 Pa·s; a 19% change.