H2Owon

My Porsche dealer workshop manager explained to me that the intercooler pipe is often pulled to ease access to sparkplugs. Either the pipe reseals upon reassembly, or it doesn't. If the seal looks hard, the pipe is replaced at the time of the spark plug change to insure it reseals properly. If it looks like the seal is still pliable, they just remount the old pipe. If you get an oil leak afterwards, it was a bad call and the fix is a new pipe. As someone already mentioned, that pipe has a seal revision to help address the issue. When mine started to leak (after a major maintenance) I was also trying to figure out what was above that pipe and leaking not realizing that you can get oil in the air intake in the normal course of operation. My car is now fitted with the revised pipe as I suspect most early 991.1 turbos are..

Foosh

Thanks for the detailed explanation. This is very helpful.