Lol, they didn't know Jeep had a diesel? They had them 7 years ago!
If they didn't know there was a diesel, they surely don't know what oil to use. It's not like its an 05 Cummins, it surely needs some type of low ash oil for the DPF and other emissions junk.
Read your manual, be informed and get the stuff yourself and find someone to do it for you. Better yet, do it yourself!
08 Limited Hemi - wheels, tires, springs...ya know, stuff