Is it legal to sell used transformer oil and under what conditions?

In many jurisdictions it can be legal only if the oil is properly characterized, documented, and sold through licensed channels. Conditions typically include verified PCB concentration, lab analysis for contaminants, traceable chain of custody, and compliance with waste and chemical product laws. If PCB content meets the definition of non PCB or below regulated thresholds, it may be eligible for recycling or re processing, but still must meet technical specs before reuse in electrical equipment. Always follow national rules and buyer requirements.