Blah, I just changed it (from mobil 1 75-90 to the same) and it came out like used motor oil (black and smelly). There was no metal shavings or anything though. The diff fluid only had at most 15k miles. I guess my question is if it it supposed to look so bad after only 15k miles? A little spirited street driving but no events

 

IIRC engine oil doesn't smell like gear oil.
After 15000 miles (it looks more like that ) oil can not be like new.
Being crushed between the pinion and ring and abused by the Torsen.
If you are living in an area where the temp doesn't go arctic you could / may / should consider using a straight SAE 90 GL-5 gear oil.
(as recommended by Honda)
LE-607.
Honda Marine SAE 90.
"Oil Journals"

 

That is strange. When I've drained OEM diff fluid, it is always nasty stinky and very dark gray.

Mobil1 on the other hand almost always comes out looking the same as when it went in. Barely any color change. My interval is 15k as well.

-Hockey