Two other ideas come to mind here for sources of red oil. 1) My coach has an oil bath type air filter. When cleaned, it is thoroughly covered with several treatments of detergent, then allowed to dry, then mist-sprayed with a red oil to completely bathe the filter material with a red oil. The red is there to make visible any skipped areas over the filter material while spraying. Once the filter material's outside surface is completely red colored, then you know it's completely covered. 2) Just above the air filter in my coach is the hydraulic oil reservoir for the (I think) cooling fan and power steering. That reservoir is filled with Dexron III. If it's leaking, then there is another source of red oil.