Between the front of the oil pan and bottom transmission mounting bolt has been covered with oil. I'm losing about a quart every few tanks. The car smells like oil, and the AOS seems like it's working (no smoke, no cats so I'd def see it).

I decided to give it a decent clean to see where the oil might be originating from.


As I got the oil off, I noticed a small hole in the bottom of the case. It's not a perfectly round hole, it looks like it's a casting issue. I tried to take the best pic I could. Pic 1 was the wide angle, I'm lying under the drivers side of the oil pan looking to the passengers side. Pic 2 is zoomed. This is behind the rear sway.

Wonder what it is, looks shiny inside.

 

My guess the leak is elsewhere and the oil is just showing up there as it shows up at other locations removed from the actual leak source.

To be sure, use some kind of cleaner that is residue free like carb cleaner, MAF cleaner or brake cleaner and clean that area well and remove any oil.

You want the area dry of any oil.

Start the engine and let it idle until warm. Rev the engine but no need to get all animal with the engine. Just raise the RPMs up to say 3K briefly then let the engine come back down to idle speed.

Shut off the engine then check that hole for any signs of oil leaking.

Check the camshaft covers and all other sealed, gasketed, o-ringed areas above for any signs of oil leaking.

'course the RMS (or IMS flange) has to be considered as a source of the oil along with the front main seal. Also, there might be a leak source under/behind the bell housing that is not the RMS or IMS flange, but if this is present this can't be eliminated until the bell housing is removed. More likely if the leak is id'd from coming behind the bell housing the RMS or the IMS flange is the most likely source of the oil.

 

@Macster, I appreciate your detailed response. It didn't go unheeded. I cleaned the entire area with Goof Off (I find I can tolerate using that in garage much better than aerosol contact or brake cleaner). I actually drove the car a couple of times and it was clear the leak is coming from the union of the transmission and rear of the engine. The area I photographed was still clean, so my guess is that it had been leaking for a while and the previous owner has never been under the car.

Anyhow, my AOS is starting to check out, so I brought the car to The Porsche Specialist in Broomall, PA. They ordered the part and are going to do the custom install. They inspected the car and felt the RMS was certainly the culprit and are going to replace when they do the AOS.

I appreciate the time to respond, the rest of the car looks relatively clean for 16 years old!

 

Glad to know you found my suggestion of some value.

Can't help but comment on the "custom install" in reference to a new AOS. AFAIK the replacement of the AOS doesn't require any custom install. Do you know what is going to be "custom" about the new AOS and its installation?