I have 2500 miles on my Armada and I am planning to change the rear diff oil. The manual states that I should use 80W-90. However the dealer told me that 05 Armada's should use 75W-140 synthetic according to an updated bulletin. The dealer also told me that Nissan updated the recommended fluid after rear diff heating issues. I also called 1800NISSAN1 and talked to steve who first said to stick with the manual but when I pressed him to get a definitive answer, he confirmed after a while that the dealer indeed was right and the rear diff should use 75W-140 synthetic. He said all 05 Armada's should come with syn 75W-140. One more side note for any of you planning to change the diff oil. The technical manual says to use High performance thread sealant. The OEM one cost over $20 but equivalnet permatex 56521 would cost about $15 -16. Just in case you did'nt notice.