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. 5.2%o2, 2 ppm, 0 smoke, 82.8% efficient System is operating properly. The circulator gaskets have corrosion on them from a previous leak. Recommend replacing them. Also the pipe on the boiler for the hi-vent is corroded from a previous leak. Recommend replacing the pipes before they start leaking.