Retaining workpiece dimensional accuracy and quality, elongated tool life, minimal surface roughness, minimum tool wear and overall high productivity in metal cutting (machining) operations are areas the cutting fluids plays pivotal role. This study focuses on surface roughness, cutting temperature and tool wear by evaluating their optimal factor effectiveness during turning of AISI 1020 Mild Steel using an environmentally friendly cutting fluid. Serious concern has been raised about the non-biodegradable and non-recyclable of the conventional (mineral based) cutting fluid and this prompted the renewal of research interest in environmentally friendly cutting fluids such as the neem seed oil based cutting fluid. The locally sourced neem seed oil (NSO) was characterized by investigating the physiochemical properties and the fatty acid composition (FAC). Surface roughness, cutting temperature and tool wear were minimized during turning of AISI Mild Steel using coated carbide insert with the evaluation compared with the mineral oil based cutting fluid. Taguchi experimental design was employed during the optimization. The formulated fluid showed 8.35 pH value, 0.896 m 2/s viscosity, good resistance to corrosion, stable and milkfish colouration. The S/N ratio for NBCF and MBCF are 800 CS, 0.4 FR and 0.6 doc; and 800 CS, 0.4 FR and 0.6 DOC respectively with R-sq and R-sq(pred) values as 98.37% and 97.38 under the NBCF and lastly 94.53% and 91.25% under the MBCF for surface roughness respectively. For cutting temperature and tool wear, S/N ratios show A 1B 1C 1 under both NBCF and MBCF. The findings shows that the neem seed oil based cutting fluid outperform the mineral oil-based fluid under the same cutting parameters and this has contributed to the science of machining.