Car is 2007 G35 Journey. My differential fluid was changed at 70k miles with Valvoline 80-90 gear fluid. Its now making an audible gear noise when going above 40mph. The oil before this was changed around 35K with Kendall 80-90 gear oil. I am pretty sure the noise is coming from the differential because I have a 2001 QX4 with similar noise when going over 40mph but louder. Anyone else experience noise issue with the Valvoline fluid? Am thinking draining it and changing it back to Kendall if I can find it locally.

 

I changed both of my differentials recently with Pennzoil 80w-90 as they were recommended and sold at my local Nissan dealer and I haven't had any problems yet. I don't think it's due to your fluid being too old as the differential oil I had before has been in my car for 100,000 kms and it ran very smoothly. Maybe when you open it up pay close attention to the magnetic drain plug bolts see if there's excess wear.