I had both leaking on my 97 Mark VIII, the oil filter adapter gasket and the sender. I think I might have broke the sender when I did the adapter gasket, or they both always leaked.
When I bought it the oil filter was way over tightened, like they thought that is what was causing the oil leak. I have over 400,000 combined miles on other 4.6 2v cast iron blocks and no problems with the oil filter gaskets on them, you see a few posts about them, but nothing like on the Mark VIIIs.
I had to pressure wash the underside of the car, the drivers side block, and really watch it to determine the oil filter gasket was leaking. I thought at first it was the oil pressure sender but there was oil coating places it couldn't be from the sender alone. I had quite a bit of oil on the ground before replacing the gasket, then with the sender leaking only it was less but still obvious.
It coated my engine, transmission, exhaust, everything with oil. Now that is all clean, no more oil coating the driveway.
This is what I would get dripping off everything when parked (this is probably parking the car over the tray 3 times:
This was after cleaning it up once and running it for a week or so.
The oil filter gasket wasn't the funnest thing I have ever done, and I struggled with it, but obviously it much easier to do than an oil pan gasket. I am sure I could do it much faster this time, removing the drivers wheel to and going through their makes a couple bolts easier than trying from underneath.
Mine was $6 at rockauto.com
