The oil filter is the ultimate depository of foreign matter that gets picked up by the swirling oil currents in the engine. As a result, it is a useful tool in diagnosing impending failure by capturing particles so they can be identified and possibly traced to a source.

Recently I had to do an oil and filter change on an 01 Boxster. I noticed some black or dark brown specs on the surface of the old oil filter. I wanted to examine the filter for trapped particles; so I broke off the ends of the filter as shown in these pictures of a new filter.

I cut through one of the folds and stretched the filter paper out and tacked it to a 2X4 as shown here.

Theses are pictures of the metal shards that I saw caught in the filter paper.

Even though the car was young in mileage, I would guess that the intermediate shaft bearing is starting to fail.

As a result, I would recommend that at every oil change on a 986/996 that the old filter be opened and inspected. I would also recommend that the oil filter be inspected in every PPI of an 986/996.