Fossil fuel–based dielectric liquid is commonly used as a refuge of all power system components. Due to environmental impacts, depletion of fossil fuel reserves and used oil discard problems encouraged the researchers to work towards alternative insulating oil for traditional mineral oil. In this work, vegetable oils like olive oil and coconut oil are mixed with mineral oil at various compositions. The key parameters such as dielectric strength, acid content, viscosity, flash point, and fire point are measured as per the standards. The experimental results show that natural ester performs better than mineral oil, and with the increase in mixing ratio, the performance of mixed liquid insulation also increased.