just got new to me 2003 suburban and have changed every oil but the transfer case, i have search a bunch of forums but i am still not sure about what transfer case oil, i have the 4x4 with the buttons 2hi, 4hi, and 4low on the dash, please advise thanks

 

I think you need that auto trak stuff. It is not cheap but hear it's good.

 

Owner's manual should tell you or you could just ask your dealer's service dept.