Greets,
Taking the subject further, there are some considerations when using oiled filter elements. The two most common filter materials are gauze(woven) and foam(cellular). The structural differences of the materials dictate the characteristics of the oil to be used. The woven material has a thinner, denser media for the air to flow through. In this case, porosity of the media is very small and a lighter oil should be used. In this way, the oil is only viscous enough to adhere to the strands of the filter media without effectively reducing the size of the air passages through the media. The woven type of media has natural small particle filtering abilities due to it's design, so the addition of a light oil to the element enhances this natural filtering. Using a heavier or tackier oil in this design can actually impair the air flow efficiency of the filter by clogging the microscopic pores of the media. By comparison, foam elements do not have the natural small particle filtering abilities because of their extremely large porosity. These filters are usually thicker as they must rely on longer contact with the incoming air to filter efficiently. For this type of media, a heavier or tackier oil should be used. This is required because the spaces that the air flows through are much larger than woven media and the oil is the primary filtering agent rather than the media. The foam merely presents a tortuous air flow path to allow a greater time for the incoming air to be in contact with the filtering oil. When using oils other than the manufacturer's, it would be prudent to compare the viscosity and tackiness in making a decision. The manufacturer's recommended oil most likely has been engineered to balance air filtering and air flow characteristics. When using different brands, look for characteristics close to that of the recommended oil........
