An embodiment of a heat exchanger according to the disclosure includes a core configured to receive and place a plurality of mediums in at least one heat exchange relationship, and a first manifold connected to and in fluid communication with the core at a first manifold/core interface. The first manifold includes a first end distal from the core with at least one port adapted to receive or discharge a first medium of the plurality of mediums, and a second end joined to the core at the first manifold/core interface adapted to transfer the first medium to or from a plurality of first heat exchange passages in the core. A plurality of first guide vanes in the manifold defining individual layers for the first medium, and a plurality of second guide vanes divide ones of the individual layers into a plurality of first discrete manifold flow passages extending at least part of a distance from the first end to the second end of the first manifold.