Lubricating greases play a key role in reducing friction and wear across a wide range of mechanical systems. Yet, conventional formulations often fall short when exposed to high temperatures or harsh operating environments. Recent progress has focused on using nanomaterials to improve their friction-related and flow-related performance. This article examines how different types of nanoparticles, such as metal oxides, carbon structures, pure metals, and composite blends, have been added to grease mixtures to boost their effectiveness. We outline the measurable gains in lowering friction, enhancing wear resistance, withstanding high pressure, and maintaining stability under heat. We also closely assess how these gains are achieved through processes like the creation of protective surface films, rolling action at the nanoscale, surface repair, and chemical interactions. The impact of nanoparticles on the flow behavior of grease with respect to aspects like thickness, response to stress, yield thresholds, and structural recovery is reviewed. Key technical hurdles include keeping particles evenly dispersed, ensuring they work well with existing grease ingredients (chemical compatibility), identifying the right dosage, and addressing safety and environmental risks. Recent developments point towards engineered particles with specific functions, better mixing methods, additive combinations with enhanced effects, and a focus on safer, cleaner formulations. Consequently, our review pulls together current findings, identifies pressing questions that remain, and supports the move from lab-based research to industrial-scale solutions.