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I hate to give you more bad new, but if that is the fluid they put in, it is the wrong fluid!! IIRC Nissan changed the fluid spec to specify Mobil 1 synthetic gear oil. It was one of the changes made when the 04's diffs were failing due to overheating from under filling during manufacture. The 04 issues brought about the fluid change and aluminum cover for 05 and up. I think my aluminum diff cover states what fluid to use as well. No way should you need to change fluid out at 7500 miles if they used the right stuff.They put their crappy fluid in, at $17.85 a quart, so if I still have this truck, I'll have to replace that in 7,500 miles.