Wondering when I should first have my rear end serviced on my 2010 S. I have 11,500 on it as of today. Thanks...

Might be a little early for that.

Can't hurt and wouldn't be a bad time to switch to synthetic if you'd like but there's no need. Follow the service intervals in your owner's manual.

Yea no real need to worry just yet on the maintenance of it. As for fluid it is speced as synthetic from the factory so that is kind of a moot point on the 2nd gen it is just a question of what quality of synthetic you choose to use.

I didn't worry to much on mine, but then I had the rear end replaced. Seems on the OR model the spider gears in the dana variant would sometimes fail, and I was one of the lucky ones to have this happen however grateful it was still under warranty.

However you might want to look into doing the rear breather mod just to be on the safe side it gets the breather up higher preventing it from getting water in or coved in mud, mine is up behind the passenger side tail light.