Mine went at 138500 K's (86,500 miles or thereabouts) Lots of smoke on start up only symptom and not every start up.
Left it at one of our local STEALERSHIPS for a couple of days so they could induce the smoke. No good, picked it up and they said couldn't find anything wrong and it would cost about $1900.00 to do a proper inspection but then still couldn't guarantee the result. I mentioned the AOS to them and they said they didn't think so.
Very embarrassing when you start up in a servo after filling up, and it got to the stage I hated taking the car out because I didn't know when it was going to smoke fart on me.
You could rely on it doing it when there were people around to bring you undone.
Took to to another specialist Porsche workshop not a STEALERSHIP, mentioned what was happening and he agreed straight away that it is more than likely the AOS. Left it with them overnight, picked it up next day and bingo, problem solved and $400.00 later. Happy with that.
That specialist now has all my work and the Stealership has lost it, including services. Couldn't believe they didn't know of the AOS problem which appears to be a common problem.
I still very rarely get a small puff of oil smoke on start up, which my specialist said some 986's and some 996 do this, no reason why but nothing to worry about, a little bit of oil in the chambers blowing out on start up, also car would have sat in the garage for a fortnight or so before it sometimes happens.