Pennzoil oils are always on the thinnest side of grade. One of the thinest 5w20 and 5w30.Why is that? Pennzoil Ultra Platinum has an API SP rating.
I'd suggest Mobil 1 Extended Performance 5w30 for all your cars, yearly is good for the Mustang. But do 5k OCI for the truck. Use Mobil 1 filters or OEM. For several bad observations with Fram I'll no longer recommend their filters.
There's never a reason nowadays to use anything other than synthetic.