 Transformer oil is a key component to the operation of power transformers, as it provides insulation between the windings and the core. As such, its quality is critical to maintaining the integrity of the transformer. Physical chemical diagnostic techniques can provide valuable insight into the condition of the transformer's oil, allowing maintenance personnel to identify potential issues before they become serious problems. These techniques include measuring the dielectric constant, conductivity, viscosity, acid number, and other parameters. By understanding these measurements, maintenance personnel can better understand the health of their transformer and take appropriate action to ensure continued reliable operation. This article was authored by John Virsilvestra Encho, Issa Fofana, Yazid Hajjaj, and others.