I had asked them about that, they said they checked it and it was super clean and at the right level so they left it. Perhaps the previous owner put in some other type that's not oem spec and that's the issue. I know they did their own oil changes w/ mobil 1 full synthetic. what's the best trans fluid to use? or the correct oem fluid to use?

 

I wud t take word on that. What ever it is most likely not synthetic. I'd find some am soil 75w 90. Some dealers will have nissan synthetic 75w 90.