The efficiency of cutting oil filtration is measured by evaluating the reduction of contaminants in the fluid before and after the filtration process. Parameters such as particle size distribution, concentration of tramp oils, water content, and microbial levels are assessed through laboratory analysis. Improvements in fluid properties like viscosity, pH stability, and clarity also indicate effective filtration. Additionally, monitoring operational metrics such as extended tool life, improved surface finishes, and reduced machine downtime provide practical evidence of filtration efficiency.