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 M1 EP 5w30 for all your cars, yearly is good for the Mustang. But do 5k OCI for the truck. Use M1 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.