What are the most common causes of transformer oil leaks and how are they repaired?

Common leak sources include gasket aging, loose bolts, cracked bushings, radiator weld defects, valve packing failures, and damage from vibration or thermal cycling. Corrosion and mechanical impacts can also compromise seals. Repairs start with locating the leak, often using visual inspection and clean up to track seepage. Tightening flanges or replacing gaskets is common. Bushing leaks may require bushing replacement. For structural leaks, welding or component replacement may be needed. After repair, oil level is restored, and the oil is tested to ensure moisture and dielectric strength remain acceptable.