Since Spring is near many of us will be changing
Oil & Filter before we venture out on the roads. This study has been highlighted here before but has been revised from what I can see, and may be worth another in depth look. There is a lot of good information here.
http://minimopar.knizefamily.net/oilfilters/index.html
On another note, last summer I had occasion to speak with the owner of Pro Power Filters, they make a cleanable filter with stainless mesh. He stated that conventional filters are in a constant state of bypass because the
oil actually does not pass through the paper within the filter, but passes along the pleats and the various contaminants cling to the fibers within the pleats of the filter paper. Not sure if this is right as I have always assumed the
oil passed through the paper and returned via the center hole. His statement got me thinking???