I looked for a link to filtration and found one on Hydraulic Systems that is a good one. These are the basics in filtration and an engine is similar, but different in the contaminates from the combustion process, IMO. I am no specialist on engine
oil systems, but did spend some time in the hydraulics industry.
I have not read all the posts, so if this is redundant then please ignore this post.
http://www.hydraulicspneumatics.com/...ydraulicFilter
Hopefully the link works.
One thing to remember, if
oil leaks out, particles (dirt) can ingress into a system.
Bypass valves are generally for cold start conditions and if the filter get plugged. Also paper filter are depth type filters and tend to "hold" dirt particles even if bypass is opened for cold start (short time). These are "multi pass" filtration systems, so the
oil is filtered many many times per minute. Particle count usually drops as the system runs, unless high wear is present or a lot of dirt is coming in from outside the sealed system (ingression).
Lee