"Dunny Roll" type filters are low quality technology mainly because the particle removal efficiency falls away dramatically, as the element starts to block.
They rely on the depth of the media pack to allow (potentially) lage dirt holding capacity, but the media pack lacks support and "opens up" and releases contamient down stream, once the differential pressure starts to rise (media starts blocking).
Users are fooled into thinking they are getting good element life, because these elements seldom achieve sufficient differential pressure (dp) for the blockage indicators to function.
However, downstream oil samples are usually just as dirty as upstream samples.
The typical (cheap) automotive spin-on element as fitted to our vehicles is better value. The media is usually cellulose (paper) and doesn't have the same surface area as the dunny roll elements, but they are more effective because they retain more particles at a higher dp.
There is much more efficient media available than cellulose, but not canned for the cheap automotive market.
It is inorganic fibre, as used in any decent hydraulic filter; developed and pioneered by Pall Corporation in the late 60's. However as used by the majority of automotive manufacturers, the cellulose media spin-on canister they use cost them about $1, and removes about one in every two of the particles of the can's rating (50% efficient); by comparison the quality hydraulic filter media would remove 999 of every 1,000 partices of the element's rating (99.99% efficient) and would cost perhaps $30.
