[Dave951]

Wow, that's a new one. These are just shots in the dark. Help me with the logic.

It seems that as the turbo spins faster and faster, it would let more oil blow by the seals. This would lower the pressure, but I can't imagine it dropping 2bar. You would definately notice smoke in the exhaust.

If you did have a headgasket break that only opened up under boost, letting oil leak by, I can imagine that too. However, it seems like you would have to lose a lot of oil in that situation as well.

Maybe it is just some wierd electric drain on the system under boost, causing the pressure gauge to display lower?!? You should try and hook up a mechanical gauge to doublecheck the electric one.

I would just be careful while you're trying o figure it out. Maybe no driving with the radio is in order, so as to let you hear the trademark tick-tick-tick of good ole #2.

Dave