Customer had a smell of oil through vents of home coming from furnace, opened furnace up which was dry no oil inside unit or combustion chamber, combusti9n chamber clean, exhaust piping clean no sign of soot, customer does have a old oil boiler that does one room in home and hot water, unit hasn’t been serviced since 2009, it’s a possible it’s very dirty and drafting down chimney of furnace, that is only scenario I can think of furnace is spotless and has new filters. We are coming to service units in February will double check systems at that time.