Performed a heating pm on an oil boiler. Brushed and vacuumed. Replaced the oil filter, nozzle and strainer. Started and checked the safeties. Performed a combustion test. System is operating properly. Several of the circulator gaskets have corrosion on them from previous leaks. Recommend replacing the gaskets. The oil on the floor under the tank appears to be old from when the tank may have been overfilled. There are streaks down the side of the tank from when it leaked out of the threads. Did not see any new leaks.