Roller cam or not, our performance engines are 50 year old technology that we easily double or triple the factory HP and the internal parts need the proper oil and care to provide durability and long life.
The tiny roller bearings see lots of load as we also up the valve spring pressure to again at least double or triple what came from the factory, not to mention much more RPM.
The street guys driving their original GN with synthetic oil and "never have an issue" also have valve spring pressure 1/2 of when new which was less than 90#'s, now 50-60#'s can use any oil as long as it does not get contaminated.
For my customers we want to see a quality oil made for performance like Brad Penn, Joe Gibbs, Valvoline VR-1 or comparable to protect our engines that cost as much as the GN!
Remember the oil ad department are not targeting our old cars, but new engines that have different design, material, machine processes and other requirements that our cars have as well as the various ranges of performance and use. Their tech department is also paid to say their oil is the best for you!
The question of the "best oil for turbo Buick" is NOT answerable with and one brand or type, but we WILL see the question again in 6 months right on schedule!