Guess it depends upon what matters most to him ...
Value
Longevity
Cost
Ease of availability
Servicability
Operating environment
Operational severity
It's likely that the engine is used in a "normal" manner, and there is no reason to suspect any high-end product is needed. (Note: "need" and "want" are NOT the same thing). With that OCI in mind, I'd say any API cert spec'd oil would do, incluing bargin house brands.
The 3.3L v-6 is an outgrowth of the old 3.0L v-6; reknowned for it's longevity. You'll likely not see any true performance or wear issues with any properly spec'd fluid, in the right grade.
You can get "better" fluids that cost more, and as long as you use them for a longer OCI, you'll get your money's worth. But for 3k miles, I'd run the least expensive dino oil I could find on sale. Same goes for the filter as well.
I had a 2000 Frontier for a year or so; as I recall it had the same 3.3L engine. Holds 3.5 quarts, uses a tiny filter, and yet the "normal" OCI per Nissan was 7.5k miles!
Some people are on a fixed budget, and need all the advantage they can get, fiscally. Others have done quite well, and money is no object. What your dad chooses as "best" for him may not be best for the next guy, but that engine couldn't care less what it had in it for 3-4k mile OCIs, as long as you stay in spec/grade.