Contribution to the analysis of the physico-chemical and rheological degradation of 15w40 lubricating oils for the optimization of drain intervals

Degradation of engine oil can lead to a reduction in its effectiveness in reducing friction, which has a negative impact on engine durability and performance. This research examined in detail the physico-chemical and rheological properties of new and used motor oils, divided into three groups (A, B and C) and subjected to different driving distances (0 km, 4000 km and 7000 km). The main findings include: Progressive degradation of kinematic viscosity at 40°C with increasing distance travelled, with greater degradation in group A. A similar degradation in kinematic viscosity at 100°C, with Group A showing the greatest degradation, suggesting a loss of efficiency at higher temperatures. A progressive decrease in viscosity index with increasing distance travelled. Significant changes in the total acid number (TAN) and total base number (TBN) of the oil with increasing distance travelled, with the greatest decrease in TBN observed in group C, suggesting acidification of the used oil. A progressive decrease in the sulfur content of used oil compared to new oil, mainly in group C. A progressive deterioration in dynamic viscosity with increasing distance travelled, particularly at higher temperatures. These results highlight the importance of regular maintenance and servicing of thermal engine lubricating oils particularly in an urban driving. future work Develop a predictive model using neural networks to analyze physical, chemical, and rheological properties, and monitor it online.