All four turbochargers on my cars (one per Volvo, two for the Mercedes) are original.
MB S600. 96,000 miles. Mobil 1 0W40. 10,000 miles/annual change (whichever comes first)
Volvo V70T5. 192,000 miles Mobil 1 0W40 7,500 miles/ annual change (whichever comes first)
Volvo XC70. 229,000 miles. Pennzoil platinum 5W30 7,500 miles
Note: all of the cars were used. All were run exclusively on synthetic since I bought them. The Mercedes used M1 0w40 only. The Volvos have had Castrol 0W30, Mobil 1 0W30, M1 5W40 TDT, M1 0W40 Euro, Pennzoil Ultra Euro 5W40, Ultra Euro 5W30, and Platinum 5W30. They’ve all been changed at the factory-recommended interval.
My recommendations for long turbo life: good oil, changed on time. Idle for the first 30 seconds. Drive slowly/low RPM for the first minute. Drive slowly/low RPM for the last two minutes. My wife’s commute allows for just that type of driving, which ensures good oil flow to the turbo on start and sufficient cooldown time.