I last rebuilt my turbo 300,000kms ago. Have been running 15psi the majority of the time, however, it will only hold 12 - 13 these days but that is to be expected. The only oil that has been put into this car is Mobil 1.
I did the valve stem seals a year ago and whilst it was off I checked out the turbo and it has negligible shaft play and there were no signs of oil getting past the seals.
I am not fanatical about changing the oil on time alone, however I do ensure that I change it once I have done 5000 - 7500kms depending on what type of driving is being done. If its all around town or towing, 5000, if majority highway 7500.
Fighting on the internet is like running in the special olympics, even if you win you're retarded.