A popular oil is Delvac 1. It is in many truck stops and truck centers such as Detroit Diesel, Freightliner, Volvo, etc. I get it locally from an independant distributor.
Cummins shops have Valvoline synthetic.
Wal-Mart and other retailers have Rotella synthetic. A bad lot earlier this year caused a big stir on the threads and I think scared off a lot of users. Not sure how the quality is today.
I wish my local NAPA had Royal Purple products. I really want the synthetic power steering fluid.
-John