A method of manufacturing a metallic foam based heat exchanger includes positioning an aluminum foam block, for example, within a housing defining a first fluid passage, and placing the block in contact with a second portion of the housing defining at least one other fluid passage, the second housing portion being an extrusion. A brazing flux material and a brazing filler are applied to at least one of the foam and the extrusion, the foam being thermally coupled to the extrusion with the brazing filler via heating in a brazing furnace. A heat exchanger includes a housing having a fluid passage with a metallic foam such as an aluminum foam therein. The metallic foam is attached to a metallic extrusion such as an aluminum extrusion, and connected therewith via a thermally conducting brazing filler. A method of cooling oil in an internal combustion engine is further provided.