Conventional wisdom on oil type...
It matters not, as long as it's changed with regularity.
For reading enjoyment, go to the E39 forum, and search "oil".
Passionate opinions, incredible scholarship, resulting in great facts (and some fiction, I'm sure) about oil, and lubrication in general.
Search for "My car crapped out because I used the wrong oil".
In our business, we expect 750k, and many get 1m/miles out of our engines.
Changed every 15k/m RELIGIOUSLY.
Best you can get for the $$$.
The "Dumb Trucker" opinion.