The good thing about these trucks is they CAN NOT be run without oil, I bet you are leaking oil from around the HPOP area, either faile IPR valve or a ICP if its an 04 or early 04.

 

Damn... Driving on that low of oil after just having an over haul on the engine. Who did the work? Did it leak prior to the work done? I agree with every one though my guess hpop, ipr, icp, icp pig tail. Those two sensors wouldn't typically be replaced if you had an overhaul done to the engine are you getting any check engine lights?