Housingless oil cooler

A core for a housingless oil cooler having alternate cooling water passageways and oil passageways comprising first and second pluralities of plate members, each comprising an aluminum base coated on one side with a first coating of a sacrificial corrosion layer and on the other side with a second coating of a brazing filler metal layer and having a peripheral rim projecting away from the plane of the plate member at the outer periphery thereof, each of the first plurality of plate members being formed so that the inner surface of its peripheral rim receives and engages with the outer surface of the peripheral rim of one of the second plurality of plate members, the surfaces of the first and second members which are in facing relation to each other having the same one of the first and second coatings to provide a passageway surrounded by layers of the same coating, at least one of the engaging surfaces of the peripheral rims of the first and second plate members having a brazing filer metal layer thereon to permit bonding of the engaging surfaces of the projecting rims of the first and second plate members, thereby providing cooling water passageways between opposed surfaces of first and second plate members having a coating of a sacrificial corrosion layer and oil passageways between the opposite surfaces of first and second plate members.