The rear is synthetic spec but the front is not, however, you can certainly use synthetic in the front if you wish. I have a 2006 and 2009 Pathfinder and I use Mobil One 75W90 synthetic gear oil in both. They have 470,000 combined miles between the two and the diffs are doing fine! It keeps me from having to stock two different types of gear oil. You're also supposed to replace the crush washers on the diff plugs, Nissan 11026-4N200.