Hi all,  When changing the oil filter the workshop manual stresses not to disturb the adapter plate. When removing the adapter plate itself the manual makes no mention I can find of replacing the adapter seal ,although it has a part number A907E6167Z. I know a lot of us have oil leaks in this area, perhaps yours needs changing. Do you know if this seal is the same dimensions as the one on the end of the fuel filter

Same seal as on the oil filter from memory. Both should be replaced every filter change.

It's a thick rubber seal, if you don't disturb it too much (and usually the sandwichplate stays where it should when changing the filter), it can be reused several times. Of course, if you do have an oil leak in that area, it is a likely suspect to investigate and easy to replace.

OE regular rubber rings are marginal and go bad after a while, they take a set and leak.

I have installed thicker Viton rings from this source  https://www.ebay.com/itm/154712146681?var=454804288982

I used them for my 90 deg oil filter adapter.

You have to decide what dimensions you may need for your particular application.