Cleaned and serviced oil boiler. The customer had the relief valve leaking a bit and she did notice it. Went through the boiler, brushed and vacuumed the heat exchanger. Changed the filter, strainer and nozzle. The relief valve went bad due to corrosion, also the two air vents are nit working properly as well. The antifreeze in the system does eat away at these components quickly, recommended to put an inhibitor in the system as well to help this. Made all recommended repairs and tested the system after. System is operational.