Hi Paul

I have seen this quite a few times, but only ever on Vauxhall Corsa 1.0 and 1.2, some have completely disintegrated.

The Mann .pdf link Paul posted...I do not really agree with as I have changed filters on these with Mann and have seen them 12 months later starting to beak up only having done 10,000 miles and 5w30 synthetic oil being used

My theory on this is that when the filter top is screwed back down it slightly crushes the filter, due to a design fault. The filter is then put under stress and over time start to break up and collapse in on itself

What finally finishes them off is running an engine flush, which takes all the paper filter debris all around the engine

Peter