Maintenance Questions

I've seen several maintenance threads but have a few questions I am still unsure about.

In a 2011 Sport, is it okay to use Castrol Syntrax Limited Slip 75-90 Gear oil in the rear differential? I've usually only done oil changes on my vehicles, but am starting to do more of my own stuff. I still have a lot to learn though.

I'm at 30,000 and had a free standard maint from the dealer and they essentially did a 25K service and I figured I'd do the rest to make it a 30K. But I'm wondering how much they did. Does a dealer normally do the items listed under the special conditions (towing and offroad)?

 

Called Oreilly's, they said that the LT in the rear isn't a problem.

 

As far as I was told when I was doing my first rear differential oil change, Limited Slip was ok on the non Limited Slip differentials. but if you had Limited Slip than you had to put in LS. there's supposed to be a sticker of some sort under the truck where you put in and drain the oil. I believe I used Mobile one with LS

 

at 30000 you want to change both diffs and the transfer case too, grease the ds whilst under there and check and tighten the driveshaft bolts at the rear axle. oh and change your spark plugs too...i just did all that to my 11 used

$30 mobil 1 75w90 mobil 1 104361 75W-90 synthetic gear lube - 1 quart (pack of 2)

mobil 1 75w90 in all of them.. youll need 6 total quarts to get er done