As far as Rotella T4 goes, I would check the recomendation date and compare the T4 specs and VOA from then to currently available product. There were major changes in the additive packages a few years ago.
That was Shell's recommendation as recently as a few months ago. There are no Shell/Pennzoil/Quaker State automotive oils with high ZDDP additive packages. So, Shell recommends Rotella.
Despite recent reformulation, Rotella still contains a fair amount of ZDDP. But as primarily a diesel oil, it has detergent packages which are far from optimal for our gas engines.
So, even though Shell pays me every month not to work, I'd recommend several alternatives that are better for most of our applications. Mobil 1 FS 0W-20 is at the top of the list.
