Horror: head wrap and/or lambda probe ???

Listen, this is a pretty horror story.

My V8 machine already had an extreme oil consumption of 3 to 4 liters per 1000 km. All known on this forum; valve collars and / or head wrap. The trip was nevertheless of the "superior running culture". Some PS losses, 0-100 went no longer in 7.5 seconds but 9.0 etc.

So once in 3 months he spits out 6 chops of black and dry russian from the exhaust, I understand. He also had quite little smoke, neither white, grey, blue or black.

And then, at once. . . I was on the A1 from Amsterdam to Bremen for 300 km. There were all the features of a defected lambda probe and / or a "broken" head pack - at the same time & together.

I drove pretty cool and very fast - so 120 / 140 kmh, once in a while short 160 / 180. I also added 2 liters (cold) motor oil to the (hot) motor on the way.

I pulled out the lambda plug today, but there's hardly any improvement. What happened? Is it possible that the head pack has burst at once? Please help.

Today's (extra) characteristics are:
- huge oil consumption, so 4 to 5 liters per 1000 km
- heavy smoking (white, grey, blue) during cold / short rides (just made a short test drive)
- restless / unstable empty run, vibrations, 7 or 6 cylinders? The famous running culture of the V8 has disappeared completely, in every rpm area
- none or quite weing pulling force in any rpm range
- a distinctly hissing noise at the right cylinder bench (passenger side), at the speed of the empty run, as-if the candle is not fixed.
- no loss of cooling water,
- temperatures of water and oil remain normal (60 - 70 degrees)
- motor oil nivo and pressure is normal - between 2 and 5 bar

My questions:
- HILFE; was köntte da passiert sein
- Can "break" a head pack at once
- where does the hissing noise come from
- was the cold oil maybe my mistake
- etc. etc.

I'm looking forward to your reply, my VAG must give a clear order.

Greetings, Harry