Why does transformer oil leak from bushings and how is it fixed?

Transformer oil most often leaks from bushings due to aging or damaged gaskets, seal shrinkage, cracks in porcelain or composite housings, loose flange bolts, or long term thermal and pressure cycling. Overfilling and blocked breathers can also increase internal pressure and force oil out. Fixing the issue usually involves tightening connections to specified torque, replacing gaskets or seals, repairing or replacing the bushing, and correcting oil level or breather problems. After repair, the area is cleaned, monitored for re-leakage, and oil quality is rechecked.