Biofuel is a sustainable and ecologically friendly energy source that evolved from the usage of non-edible oil and has witnessed substantial growth in demand in recent decades. Biodiesel is primarily made from organic sources, such as edible and non-edible vegetable oils, and is then profiled before use. This research will look into the potential of producing biodiesel from neem oil. The biodiesel was made utilizing a trans-esterification procedure that gave saponification values of 191 mg KOH/g, iodine of 10 mgl2/g, acid of 14.0 mg KOH/g, the density of 0.91 g, a viscosity of 23 mm2/s, and flash point of 266 °C. The improvement of lubricating oil characteristics is crucial for protecting engines, bearings, and machine components from friction and wear, as well as minimizing energy spent combating friction. Lubricant tribological and rheological properties are crucial for wear prevention in unchanged environments. The use of particle and filamentous nanofillers increases these properties, allowing the lubricating oil to be more stable under extreme working conditions. The purpose of this study is to investigate the improvement in neem biodiesel performance following the addition of multiwalled carbon nanotubes (MWCNTs) in six modest compositions, namely, 0, 0.03, 0.06, 0.09, 0.12, and 0.15 wt.% MWCNT. Besides this, the additions of MWCNTs have been studied and documented in terms of flash and pour points, thermal conductivity, kinematic viscosity, friction coefficient, and wear. The MWCNTs were characterized using X-ray diffraction. The addition of MWCNTs raised the pour point and flash point, although there was unpredictability after the 0.09 wt.% composition. Thermal conductivity and kinematic viscosity are enhanced continuously and notably. The friction coefficient and wear scar diameter were lowered to 0.09 wt.% MWCNTs before reversing attributed to accumulation and non-uniformity. When all of the studied attributes were taken into account, a composition of 0.09 wt.% was determined to be optimal. This formulation provided improved tribo-film and hydrodynamic lubrication consistency was maintained.
