Serious design flaw in oil filter assembly?

[mk2]

People have I got this wrong or is there a problem with the element style filters vdub are using on many of their cars now (and on the Lupo TDI engine)?

So the oil pump pumps up 'dirty' oil from the sump, first straining any big lumps out using a mesh. The oil gets pushed up, into the space on the outside of the filter, through the filter media, and then into the centre, where it then feeds out to the engine. No problem, it's how all oil filters I've seen work. all good.

The problem is that with the element style filter, as you unscrew the cap to change it, the contaminated oil along with lots of crud will flow into the clean oil feed gallery. Or at least that's what I've worked out. Yeah, true, most of it goes into the sump to get flushed out, but some naturally will cross contaminate the clean side.

Or am I missing something?

Edited October 17, 2022 by mk2
diagram from self study guide added

[ObjectiveAway]

I have seen this before and for the first time fully understanded what are you trying to show. I think the few drops of oil in clean oil feed is nothing bad, because the oil have already gone through oil pump and all solid particles is already catched in oil filter cartige. They already did good job by making port to move the old oil straight back to oil sump.

[mk2]

I prefer the screw on filter types. Maybe not as easy to swap, but you can prefill the filter, and there's never any cross contamination, where particles of dirt can be introduced into the clean oil feed.

[ObjectiveAway]

On 10/25/2022 at 1:23 AM, mk2 said:

I prefer the screw on filter types. Maybe not as easy to swap, but you can prefill the filter, and there's never any cross contamination, where particles of dirt can be introduced into the clean oil feed.

The only thing I like better in replaceble filter cartiges is that you can easily breake them apart and see if there is something caught in them.