Towards the end of the Hastings depth type production, I was at a filter workshop put on by a tech rep from Purolator. He explained their testing found that the cotton-like bulk fiber media in the Hastings filter could allow for oil to find a path of least resistance, allowing the oil to pass through virtually unfiltered. Further, that pleated paper media wouldn't normally allow that to happen.I believe it was a Hastings depth-type spin-on (probably a T225?) for my parents' 1972 Chevy Nova 250 straight six around 1983 or so. Those were interesting filters. I would like to see how well those worked compared to a standard paper element spin on filter.