Abstract: A top or bottom mounted, in-line, in-tank return line filter element is mounted in a hydraulic reservoir. The reservoir includes a holding tank, at least one outlet extending from and one return line extending to the reservoir, an in-tank return line within the reservoir and extending to one return line, and an in-tank return line filter element mounted within the in-tank return line. The in-tank return line filter element includes an end cap, a filter media and a by-pass valve coupled thereto. The end cap includes a central fluid opening, a mounting surface for the filter media, and a peripheral attaching mechanism for attaching the filter element to the in-tank return line to form a filter assembly. The mounting surface is positioned between the central opening and the attaching mechanism such that an in-line, in-tank filter element is provided.