Thick oil smoke ONLY on decel in gear..WHY??
 

What the hell... I'm trying to sell my car, and suddenly it starts smoking.

It ONLY smokes (and it is definately oil) when I'm decelerating in gear- so it's only during very high manifold vacuum.
It's thick too- like a cloud in my rear veiw mirror.

I can't think of any reasons why this would be happening.
My oil pan is under vacuum- which is where the turbo drains- so I doubt it would be the turbo oil seals, since the vacuum really assists the drain. It was perfect untill a few days ago. There was nothing that happened either, I just suddenly noticed it.
What the hell?
It doesn't do it at any other time, not during aceleration, or idle.

Two options here.... Check the turbo (easy) or check the oil control rings and "o" rings in the engine (hard).

Sounds to me like a blown turbo. Its been my experience that they do this when theyre blown. Im sure it could be other things though...

Sounds exactly like what was happening to me when my turbo seals took a shit.

Does it smoke coming down from all/any RPM? Or just the upper range of engine speed?

My old 12A began smoking ~5K+ on decel....then it just progressed down to 3K...anything over 3K and let off the gas and voila instant james bond smoke screen.

Miles on the motor/turbo?

How long did that take to happen (smoke @ lower RPM)?

Did you ever tear that thing apart to see what it was?

from what I read from this site in terms of looking at specific items when buying an FC, it sounds like the o-rings of the rotors...

It started smoking with ~178,000 miles on it. Started smoking lower about 3-4000 miles later, then pretty much all the time ~185K when I parked her. Never tore the motor apart, but all signs point to the O-rings in that one.

Ahh I see. :)

I've got a problem like that sort of. I'm more suspicious of my MOP than anything. Decel after hitting redline or revving to redline will conditionally (sometimes) make some of the blue stuff. I've been paying much attention to my MOP lines. I think that's where the problem is, rather than sideseals. (My car has the equivalent of.. roughly 120,000 miles).

I've been strongly considering lately rebuilding the thing over winter. Not sure if I should. Compression is strong, but I was thinking it might be good as a learning experience and to do it before the unthinkable should happen.

Sometimes it could be caused by a bad OMP linkage. make sure your OMP is not stuck wide open.

S5 OMP is electronic.

Engine only has 2000 kilometers on it.
It could be the turbo, but if that was the case, why wouldn't it blow smoke all the time??
I'm thinking the oil rings in the engine, with the wigher vacuum pulling the oil through them.