Just purchased this 2017 Nissan Titan SV used but no way of finding what oil was used.
What's the most popular brand used in these 5.6 Liter engines?
Most popular - couldn't tell you. Titan talk can probably help you there.
What I can tell you is this gem of an engine shears oil like a puppy going after the Sunday paper.
Under towing loads it will shear almost anything a full grade down in 7500 miles.
Since 04 I've run everything from 20 for short 3K OCI's to 50 in it, and it's had a very hard life of towing and hauling.
It got fed mostly 0W-40, but Its quietest and "sounds" most happy with 5w-30 Mobil 1 EP.
My advice with any DOHC chain driven engine is to run the very best filter you can get and magnets to keep as many particles as you possibly can out of the chain once it wears past the tensioners range you've got a real job on your hands.
Ive run a Fram ultra XG7317 and magnets on the cans since very early on.
My "ancient" 04 titan crossed 100K just a month or so ago and I have no intention of getting rid if it.
The new NA gas trucks aren't better enough to force my hand and the titan with a tow rear end will still put lots of brand new half tons on the trailer 15 years after its introduction.
Congrats - enjoy.