Hey Brian, I wonder if you could seal that leak with some JB Weld, or something...
You probably don't have any "cracked" or damaged steel...just "O" rings or gaskets leaking. If the adaptor is broken, I'd be very cautious about welding or repairing the thing. Get into all sorts of alignment and porosity issues. My SWAG is that the adaptor is OK, just needs gaskets and seals. I'd replace the adaptor if it proves to be cracked. Hate to ask what the adaptor costs...there may be good used on the market now...used engine parts are showing up for S60s now. I wouldn't use any epoxies, even though they are amazing quickie repair items, on a critical part such as an oil filter adaptor.
Brian, Dina one ebay...salvage title.......parts room in a bus....Item. 180038567129