within the scope of the present invention to provide a single mounting plate 14 with the recess 30 suitably produced in the plate 14 for example by a metal removing process such as milling as illustrated in fig3 a 4 a 5 and 6 impressions 36 may advantageously be provided in the inner surface 18 of the outer plate 14 b near and around the openings 32 in the outer plate 14 b during manufacture of the oil cooler 10 the impressions 36 provide a solder depot for solder from the inner surface 18 of the outer plate 14 b to prevent solder from flowing during the soldering process onto the sealing surface 38 of base plate 14 a the impressions 36 are illustrated in fig5 as having interruptions 39 see e g fig5 but they can also be made continuous seals 40 may advantageously be mounted in the mounting plate recess 30 in accordance with the present invention the seals 40 may advantageously include projections 44 see fig3 a formed on their outside to assist in securing the seal 40 in the recess 30 so that it cannot fall out during installation of the oil cooler 10 further as best illustrated in fig4 a 4 b the openings e g 20 in the base plate 14 a are smaller in cross section than the corresponding openings in the outer plate 14 b so that the seal 40 may be pressed into the recess 30 without risk that it will be pressed too far e g into the oil cooler 10 as a result a tight.