Abstract: A tank truck is provided for transporting a variety of fluids such as water, petroleum products or drilling mud and includes an agitator comprising a pair of horizontally disposed longitudinally aligned agitator elements each including a longitudinally extending helical flight. The agitators are supported at their adjacent ends by means of a releasable and removable bearing and by outboard bearings at the ends of the tank which allow limited articulation of the augers to facilitate their removal with portions of the auger shafts extending outwardly beyond the outboard bearings to reversible drive motors which turn the augers during operation in the same or opposite directions so that different modes of operation can be used for transporting the fluid by both augers in the same or opposite directions. The invention also includes pivotable spray heads mounted in the tank for washing the tank with heat exchangers provided for transferring engine heat to the tank contents and to the washing fluid.