cp3, What you are thinking is very true.
However, how do we know when/if an oil filter goes into by-pass mode? We don't!
When a filter is in by-pass there is nothing to catch any hard pieces, fragments or grains of Iron or Steel that might happen to be pumped into the filter. The hard metals that can cause scoring and possible damage are the metals I'm concerned about most. Metals like aluminum, lead and copper are all soft metals...so the concern is not imperative, if the filter is in by-pass and these metals are present. Nothing is truly "fail-safe" at stopping all hard metals from entering the engine if the filter is in by-pass.
Who knows for sure if all, or some, oil filters catch 100% of the iron and steel from engine wear, 100% of the time???
Originally Posted By: cp3
Has anyone had particle counts done with and without magnets? I am wondering if they are just catching stuff that would be caught in the media anyway.