A monobloc piston assembly has at least two parts fixedly joined together forming a piston body having an oil cooling gallery. The oil cooling gallery is defined by an upper wall, a lower wall, and a pair of radially spaced inner and outer annular walls. A skirt is formed as one piece and of the same material with at least one of the two parts and depends generally along a longitudinal axis from the lower wall. A pair of pin bosses are spaced laterally from the longitudinal axis and depend generally from the lower wall. At least one elongated opening extends generally between the pin bosses with the opening preferably spanning a substantial portion of the distance between the pin bosses. Oil flows into and out of an oil cooling gallery through the opening.