How to cut open an oil filter and inspect.
I bought a inexpensive oil filter cutter from Ebay ($38 Shipped)
It is a decent enough tool, simple solid design, with rollers.
Twisted 3 times and the filter can was cut.
It will leave a sharp edge on both the can and the filter mount.
I cut the oil filter that came on a 1.8L BP Mazda engine
It has a rubber anti drain back.
I lifted the filter cartridge from the mounting plate.
Nasty as all get out.
Looking around it, I noticed a large rip to the core, This allowed unfiltered oil through the engine.
Also looking into the folds I saw metal flake
Taking my pocketknife, I cut the filter media to remove the tin end caps.
Now the tear on both sides of the crimp.
It also has a tin perforated core.
Now, unrolling the filter media, and looking at the bottom of the pleats, I can see just how much metal flake there is.
At this point bearing damage would be a concern.
The whole engine should be pulled down and all oil galleys plugs and jets cleaned and inspected for metal debris in the oil galleys.