The purpose of this project is to examine whether the industrial shell and tube heat exchanger, 2-pass tube side, suits the process of cooling the mineral oil used to lubricate the plain bearing of a mill drive. The cooling water, amounting to 1 m3 of hourly discharge, flows in two passageways through the pipe bundle which consists of 44 copper pipes with the outer diameter of 10 x 1 mm and the length of 404 mm. Mineral oil, with the discharge rate of 8 L/min, flows inside the shell and around the tube. The pipes are laid out in a triangular fashion and pitched 13 mm apart. There are 6 baffles inside the shell. The results of examination indicate the laminar flow inside the tubes and shell (Re < Re,c). Until the oil temperature, tU, rises by 5,5 oC the surface required to exchange the heat is smaller than the total available surface; a multi-tube exchanger possessing the aforementioned characteristics exhibits satisfactory rates of cooling the mineral oil. As the oil temperature, tU, rises upward of 5,5 oC the surface required to exchange heat also rises compared with available surface, while the multi-tube exchanger no longer fulfills the requirements for cooling the mineral oil.