One theory is that oils build up on the road surface. https://blog.response.restoration.noaa.gov/oil-water-and-dangers-spring-showers https://blog.response.res

One theory is that oils build up on the road surface. https://blog.response.restoration.noaa.gov/oil-water-and-dangers-spring-showers https://blog.response.restoration.noaa.gov/oil-water-and-dan...