Abstract— Various vegetable oils are subjected to standard experiments, and the results are discussed in detail. The changes in mechanical and electrical properties of these oils, observed during standard laboratory tests, are studied. The main insulation characteristics of these oils include moisture content, acidity, flashpoint and others are compared with standard transformer oil. The tests were repeated several times to verify the reliability of the obtained results. Although the long-term use of such oils can better prove their performance, the outcomes of the laboratory tests are significant here to prematurely exclude the oil types which have poor insulation characteristics. Similarly, the current testing approach is necessary to verify the ability of available testing machines to accept certain types of oil with various chemical characteristics. The relationship between flammability and combustion concepts are clarified in the analysis of liquid insulation properties. One of the significant results in this study is the high flashpoint shown by all vegetable oils examined in this work compared with mineral oil. The olive oil was used as an example to show the effect of filtration on reducing moisture content and other impurities by comparing the performance of the oil before and after the process. This study applied two approaches-general and specific- to prioritize vegetable oils. In general approach, a broad classification of vegetable oils compared to mineral oil was given, whereas in the specific approach a numerical scoring system was generated to identify which oil performs best, taking into consideration the technical and economic factors.