[88carrera]

As Robert has indicated previously, these are two very different issues. Neither of them is unheard of with the 996. The air oil separator (AOS) is known to fail such that smoke is generated. An inconvenience, but if the one on the car you are considering has been replaced, I would count it as no big deal.

The IMS seals are also known to leak, not the same as a rear main seal (RMS). The most troublesome issue with the M96 engines is, as Robertt has pointed out, with the bearing on the intermediate shaft. I suggest that you search for IMS bearing issues on this list as well as on the Renntech or Rennlist sites. There are ways to deal with this if you are afraid that one might fail. I replaced mine with the LNE ceramic bearing when I did a clutch replacement at ca. 45K miles and I sleep well at night. I really appreciate my 996. What a bargain for the performance that you get!