A heat exchanger, in particular an oil-air cooler, for heat exchange between a first fluid and a second fluid, having at least a first row and a second row of tubular elements for the first fluid, a flow channel for the second fluid between the first and second rows of tubular elements; a collection vessel at one end of the tubular elements; and a distribution vessel at the other end of the tubular elements. Guiding elements for guiding the second fluid extend along the flow channel between the outer sides of adjacent tubular elements of the first and second rows of tubular elements. At least one adjustment device is provided for adjusting the relative position of two guiding elements about a pivot axis.