[jhandy]

For what it is worth I got this explanation from a respected Porsche mechanic.
The factory Bering has a plastic seal that locks in the factory grease.
The plastic seal is crappy and engine oil seeps in and washes out the factory grease.
Low engine revs, low internal pressure, long oil change cycles allows the old poor quality motor oil to stay inside the Bering rather than a pressure forced change.
As a matterof fact if you can not afford the IMS retrofit/repair, I was told to fully remove the factory crappy plastic seal entirely so that clean motor oil can bathe the berings at the very least.

Just passing along what I was told.