Help! My newly-installed oil filter leaks

I changed the oil in my 1999 996 Carrera coupe with a new Wix oil filter. Everything appeared to go smoothly, but when the engine was started, oil leaked from the interface of the lip of the plastic filter cap and the engine itself. I had never done an oil change on this car. The WIX filter appears to have plastic inserts on both ends of the filter that protrude slightly, whereas the original Porsche filter has no such inserts, and are entirely flat on both ends. I had installed the entire filter assembly, using the recommended 19 pounds of torque and a new rubber gasket ring that came with the filter. The ring was lightly lubed before inserting it onto the plastic cannister. The WIX cartridge was pushed into place (solidly, so I thought), followed by placement of the plastic cannister. I don't know what I did wrong, and wonder if my installation was faulty, or if I should just bite the bullet and install an original Porsche filter cartridge so as to duplicate the original one that didn't leak. I don't know if plastic inserts, such as the ones found on the WIX filters have anything to do with the problem or not. Any advice would be appreciated; the car is in the garage, waiting for the WIX to be reinstalled, or a brand new Porsche filter to replace the WIX. Right now, I am stumped.

Stay with the Wix filter, it is a much better unit than the OEM. It is the only filter we install in the OEM canister. Most DIY oil filter changes we see that are leaking is because of problems with the o-ring on the canister; usually one of three things: the O-ring is pinched or cut, it is in the wrong place, or there are now two O-rings (you would be amazed at how often we see that one).

I think I may have found the problem. The plastic housing's threads display about a 1.5 mm space between them, UNTIL the threads terminate, after which a much wider non-threaded space is present to evidenty allow for the large O-ring seal. Below this space is a lip that protrudes outward, and which a reasonable person might assume that the O-ring should be placed right next to the lip to provide a seal. IIRC, I placed the O-ring on the lip. I don't know how the plastic cannister/housing fits against the engine block, and I don't have a shop manual. It seems odd that the Germans designed the housing this way, and to a novice such as me, it is confusing. Question: Am I on the right track, and should I merely reinstall the entire filter, using the O-ring position as I have described? Also, why not just place the cartridge inside the cannister and merely screw the whole thing in at one time, rather than pushing the cartridge in, then screwing the cannister on? Or is this too logical? Thanks, Smitty

You are way over thinking this process. If you pull off the canister, the only thing that has to be replaced is the O-ring, which sits like this:

At this point, I am going along with the misplacement of the O-ring. Great German engineering. I see no reason why they made it as complicated as they did, when they could have included a simple spin-on type filter arrangement, such as is found on every American car on which I have changed the oil: the rubber gasket is at the top of the filter, instead of at the bottom, where it is easy to be misplaced. I understand that a spin-on adaptor is available, and I may well decide to make the change-over at the next oil change. Smitty