In today’s fast, globalised world, lubrication has become essential in enhancing engine efficiency, including in the marine sector. While the number of fishing vessels increased, so did the environmental pollution issues, due to inefficient engines. An outboard engine oil’s tribological, oxidation and thermal conductivity behaviour play a crucial role in improving the quality of an outboard engine’s life. In this research, Ti3C2Tx MXene nanoparticles with different interlayer spacing were synthesised via an advanced microwave–hydrothermal approach. Later, the nanoparticles were dispersed in TC-W outboard engine oil to formulate the Ti3C2Tx MXene nanolubricant with different concentrations. The results show that nanolubricant with a 0.01 wt.% Ti3C2Tx MXene concentration with higher interlayer spacing reduced the coefficient of friction, and the average wear scar diameter by 14.5% and 6.3%, respectively, compared to the base oil. Furthermore, the nanolubricant with a 0.01 wt.% concentration of the Ti3C2Tx MXene nanoparticle showed an improvement of 54.8% in oxidation induction time compared to the base oil. In addition, MXene nanolubricant established a more than 50% improvement in thermal conductivity compared to the base oil.