Standard gear oil.
Add LS additive as required (if your 8.8 has limited slip).
Its a waste of money to run high dollar oils in a differential. Especially if your going to change it frequently due to wheeling in wet conditions. My 2 cents.
[B]03 Rubicon[/B] (Weekend Toy) [URL="http://www.jeepforum.com/forum/f176/marshals-03-rubi-2822258/"]Build thread[/URL]
[B]11 Ram 2500 [/B] - H&S tuned 6.7 Cummins (DD/Tow Rig)
[B]05 Liberty Limited[/B] (Wife's): Minor mods, OME/JBA Suspension, 245 70/17 Duratracs