Usually when a car consumes oil with age, the only remedy for it is thicker oil so that it leaks out slower. Some people use additives like lucas oil stabilizer, but those are just thickeners and have no real positive chemical properties outside of oil thickening. So you're better off just stepping up a weight in whatever good quality oil you chose.
but...... Nissans are a little different. Theyre real sensitive about crank case ventilation. Need to keep your PCVs clean. The oil youre consuming is probably just being sucked down your intake.