About 15 years ago, my neighbour had an aftermarket turbo on his Volvo - 18lbs boost, it really went hard.
He always maintained that GTX was good enough for any turbo, and wasn't a fan of idling down.
Turbo 1 went very quickly, so he started idling down.
Turbo 2 lasted longer, but not to an outstanding degree.
With turbo 3, he bought out the entire stock of Agip SINT 2000 for about $10 per litre even then.
Was supposed to be non-compatible with mineral oil, so I've no idea what it was.
Turbo 3 lasted until he bought a boat, then threw a chev V-8 into the Volvo for better towing.
The Agip oil went 6,000km in the Volvo, then 10,000km in His Datsun.