The present work aims at investigating the lubricating oil degradation through long term durability study of compression ignition engine. A comparative assessment has been carried out for the operation of diesel and Karanja oil methyl ester as per IS 10,000 standards in two phases. In both the phases, the newly modified compression ignition engine has been operated for 256 h in 16 cycles of 16 h duration in each cycle. The lubricating oil samples have been collected at regular interval of 48 h of operation in both the phases and various physical properties of lubricating oil were tested in order to analyze the diesel engine life. Furthermore, the wear debris of all engine components was also estimated using Inductive Coupled Plasma- Atomic Emission Spectrometry during this tribological study. The results showed that total base number, kinematic viscosity and flash point of lube oil were perceived to be lesser in Karanja B100 operated engine. On the other hand, the pentane-benzene insolubles, density, moisture and ash content are observed to be higher in Karanja B100 operated engine than that of diesel operated engine. The concentration of wear elements was found to be higher in the lube oil samples which have been drained from Karanja B100 operated engine as that of diesel operated engine. The various parameters with respect to the surface profiles of the cylinder liners were recorded and compared in order to quantify the amount of wear for the cylinder liners of both engines. The percentage of weight loss piston rings is found to be higher in Karanja B100 operated engine. © 2021 Elsevier Ltd