As a member of a family that runs 3800 I must chime on.
It is certainly a reliable engine that you can run almost anything in** (except a 5W20 LOL)
M1 Trisynthetic 10W30 caused elevated noise, albeit harmless bases on oil analysis data here.
M1 SS is pretty quiet.
M1 15W50 was pretty smooth stuff, no irregular oil pressure either.
Delo 400 15W40 HDEO, it liked that too, and winter starts were no problem! (quite surprising to me)
Although I recommend a synthetic for better engine cleanliness.
With all the oil hoopla on this forum, one thing we always have to point out is:
It does not matter how superior your oil is if your engine is engineered/assembled/low durability badly.
In the case of the buick lineage 3.8 engine family it is well designed and can give you many years of service if oem service paramaters are honared.
Running synthetic is additional pride and peice of mind while you happily enjoy the great low end toruque