A heat exchanger and a method of manufacturing a heat exchanger having an internal conduit for conducting a fluid, and a heat dissipating body for dissipating heat of the fluid. The heat dissipating body has a cavity extending in a longitudinal direction. An end piece of the internal conduit extends inside of the cavity and has an orifice facing a bottom surface of the cavity for feeding the fluid into a bottom area of the cavity. An inner shell of the heat dissipating body includes a first portion and a second portion, each portion having at least two ribs transversally displaced in relation to each other. At least one rib of one of the first and the second portion is transversally displaced in relation to each rib of the other of the first and the second portion.