Arrived call for issue with oil smell, assessed the area and found oil in the return duct leading to the smell all through the house, me and Joe discussed solutions and came up with me pulling the blower climbing inside the return and wiping down the duct by hand. After entire return duct was cleaned I went to the other side of the wall and vacuumed all of the oil dry and put down power and let it sit before vacuuming it up. Went to the registers in the house with customer to show him the vents no long smell like oil and he seemed satisfied with the repairs.