A plate type heat exchanger for an oil cooler, comprising: at least two heat exchanger members each enclosing a respective first channel; an inlet oil port, for feeding a medium to the first channels, and an outlet oil port, for extracting the medium from the first channels, wherein a second channel is formed between the at least two heat exchanger members, a medium present in the second channel being isolated from a medium present in the first channel, and the second channel being arranged to communicate with a cavity in which the heat exchanger is to be mounted; wherein at least one of the heat exchanger members presents a through hole or through recess (9, 11) spaced from all peripheral edges of the heat exchanger member and extending from one face of the heat exchanger member, through the first channel, to a second, opposite face of the heat exchanger member and providing access from outside the heat exchanger to the second channel, wherein heat exchanger plates (17, 18) of two separate heat exchanger members, which heat exchanger plates (17, 18) face each other, present at least one respective protrusion (170, 180; 170', 180'), arranged in the immediate vicinity of the through hole (9, 11) and/or of the oil ports (3, 4), and wherein the protrusions (170, 180; 170', 180') abut each other, a rear side of the heat exchanger comprises a mounting flange (2a, 2b) for fixating the heat exchanger by a bolt to the wall of the cavity, said bolt engaging the mounting flange (2a, 2b) and being accessible through the through hole, and wherein the mounting flange (2a, 2b) has a surface extension substantially smaller than the surface extension of the face of the at least two heat exchanger members. at least two heat exchanger members each enclosing a respective first channel; an inlet oil port, for feeding a medium to the first channels, and an outlet oil port, for extracting the medium from the first channels, wherein a second channel is formed between the at least two heat exchanger members, a medium present in the second channel being isolated from a medium present in the first channel, and the second channel being arranged to communicate with a cavity in which the heat exchanger is to be mounted; wherein at least one of the heat exchanger members presents a through hole or through recess (9, 11) spaced from all peripheral edges of the heat exchanger member and extending from one face of the heat exchanger member, through the first channel, to a second, opposite face of the heat exchanger member and providing access from outside the heat exchanger to the second channel, wherein heat exchanger plates (17, 18) of two separate heat exchanger members, which heat exchanger plates (17, 18) face each other, present at least one respective protrusion (170, 180; 170', 180'), arranged in the immediate vicinity of the through hole (9, 11) and/or of the oil ports (3, 4), and wherein the protrusions (170, 180; 170', 180') abut each other, a rear side of the heat exchanger comprises a mounting flange (2a, 2b) for fixating the heat exchanger by a bolt to the wall of the cavity, said bolt engaging the mounting flange (2a, 2b) and being accessible through the through hole, and wherein the mounting flange (2a, 2b) has a surface extension substantially smaller than the surface extension of the face of the at least two heat exchanger members.