Those 4cyl Nissans are great trucks. Many people have 300k+ miles on them using whatever oil they could get ahold of, so just pick any decent oil on sale and run it...that's just what I would do though lol
I run Mobil 1 HM 5W-30 in my '94 Hardbody without about that mileage. I bought it in '95 and it received dino oil at 3500-mile intervals. It still doesn't consume oil between 7500-mile changes these days. It's my third vehicle now, used mostly for farm work. Nonetheless, I plan to keep driving it until the wheels fall off.
If yours doesn't burn oil, stick with 5W-30 or 10W-30. Thicker oils cause problems with the timing chain tensioner on startup.
At our place it would be Rotella 5W-40 T6 or Mobil 1 High Mileage 10W-40 to get the Moly. Four ounces of Archoil AR9300 could be a plus if you are serious about a half million miles. We have a S10 with that many miles but the body is so worn it is a struggle to keep up.
I plan to get a gallon and test it in everything over the next year so I have no experience with it yet in gas/diesel engines that are high mileage.