An oil temperature regulator assembly fluidly connectable to an oil circulation system of an operating vehicle group, for example a power group or a drive group or a gearbox group, and to a cooling system of said operating group or of said vehicle, wherein the oil temperature regulator assembly identifies a vertical axis (V-V) and two longitudinal axes (X-X; Y-Y) lying mutually orthogonal to each other, wherein said assembly comprises: i) a heat exchanger comprising, along said vertical axis (V-V), an upper exchanger plate, a plurality of intermediate exchanger plates, and a lower exchanger plate, wherein the stacking of said plates defines an oil flow zone and a cooling fluid flow zone comprising a plurality of planar oil flowing regions and a plurality of planar fluid flowing regions, respectively, alternating with one another along the vertical axis (V-V) and comprising inlet and outlet vertical oil ducts (41, 42) and inlet and outlet vertical fluid ducts (61, 62) fluidly connected to the respective planar flowing regions (40, 60); ii) a base device, engaged with the lower exchanger plate, comprising inlet and outlet oil connection mouths (31, 32) fluidly connected to the inlet and outlet vertical oil ducts (41, 42), respectively, adapted to fluidly connect the heat exchanger to the vehicle operating group; wherein the upper exchanger plate or the base device comprises an operating opening (27, 37) vertically aligned with a vertical oil duct (41, 42) and an oil circulation duct (29, 39), wherein the operating opening (27, 37) is connected to the oil circulation duct (29, 39); wherein the oil temperature regulator assembly further comprises: iii) a filtering unit; the oil temperature regulator assembly is characterized by the fact that said filtering unit extends along a filter axis (F-F) insertable as a cartridge, through the operating opening (27, 37), in the vertical oil duct (41, 42), wherein said filtering unit comprises a filtering element adapted to filter solid particles from the oil and wherein the filtering unit comprises a connecting portion adapted to be housed in the oil circulation duct (29, 39) comprising a connecting opening through which the vertical oil duct, preferably the clean side, and the oil circulation duct (29, 39) are in fluid communication. i) a heat exchanger comprising, along said vertical axis (V-V), an upper exchanger plate, a plurality of intermediate exchanger plates, and a lower exchanger plate, wherein the stacking of said plates defines an oil flow zone and a cooling fluid flow zone comprising a plurality of planar oil flowing regions and a plurality of planar fluid flowing regions, respectively, alternating with one another along the vertical axis (V-V) and comprising inlet and outlet vertical oil ducts (41, 42) and inlet and outlet vertical fluid ducts (61, 62) fluidly connected to the respective planar flowing regions (40, 60); ii) a base device, engaged with the lower exchanger plate, comprising inlet and outlet oil connection mouths (31, 32) fluidly connected to the inlet and outlet vertical oil ducts (41, 42), respectively, adapted to fluidly connect the heat exchanger to the vehicle operating group; wherein the upper exchanger plate or the base device comprises an operating opening (27, 37) vertically aligned with a vertical oil duct (41, 42) and an oil circulation duct (29, 39), wherein the operating opening (27, 37) is connected to the oil circulation duct (29, 39); wherein the oil temperature regulator assembly further comprises: wherein the upper exchanger plate or the base device comprises an operating opening (27, 37) vertically aligned with a vertical oil duct (41, 42) and an oil circulation duct (29, 39), wherein the operating opening (27, 37) is connected to the oil circulation duct (29, 39); wherein the oil temperature regulator assembly further comprises: iii) a filtering unit; the oil temperature regulator assembly is characterized by the fact that said filtering unit extends along a filter axis (F-F) insertable as a cartridge, through the operating opening (27, 37), in the vertical oil duct (41, 42), wherein said filtering unit comprises a filtering element adapted to filter solid particles from the oil and wherein the filtering unit comprises a connecting portion adapted to be housed in the oil circulation duct (29, 39) comprising a connecting opening through which the vertical oil duct, preferably the clean side, and the oil circulation duct (29, 39) are in fluid communication.