An automotive heat exchanger (10) has a heat exchanger core (12) including a header part (16) with a plurality of heat transfer tubes (38) and a head tank (20) with an opening receives end portions of the heat transfer tubes (38). A plastic header plate (18) is secured with the header tank (20) and header part (16). The header plate (18) includes a plurality of apertures (24) extending through the plate (18) that enable fluid passage. Each aperture (24) includes a cutout portion (28) that receives an end of a heat transfer tube (38). The cutout portion (28) has a complimentary shape to mate with the end of the heat transfer tube (30). A seal (50), in the cutout portion (28), seals the end of the heat transfer tube (28) with the header plate (18).