Embodiments of a hydraulic reservoir cooler include a backward curve centrifugal fan located rearward of a vented front cover of the cooler, the centrifugal fan having a center point “c” and a radius “r”; and a core area including fins and a manifold in fluid communication with a hydraulic fluid tank, the core area being located between the vented front cover and the backward curve centrifugal fan and including: a straight vertical portion extending in height less than an uppermost upper end of the centrifugal fan; a straight horizontal portion located above the uppermost upper end of the centrifugal fan; and a curved portion connecting the straight vertical and horizontal portions, the curved portion having a center point “C” and a radius “R”; where C is located above c and R is greater than r. The cooler may be adapted for use with an agricultural pumper truck.