Performed heating tune up on Carrier system. Met with tenants. Cycled system for heat. Verified proper heating sequence of operations. Checked electrical and heating components. Cleaned off blower wheel assembly as well as heating compartment. Cleaned flame sensor. Ran system through 20 point inspection. Indoor blower wheel is dirty, and motor has started to leak a significant amount of oil. Secondary motor control within range. Gas pipe has no sediment trap.,pulled limit switch and evap coil cover to inspect heat exchanger. Filter is extremely odd size, advised tenant to replace at earliest convenience as it was very dirty. System is operational but is very old and very inefficient. Tried contacting homeowner but calls going straight to voicemail. Will email invoice and findings over. System is operational upon departure.