Heat exchanger

A heat exchanger comprising:

• a plurality of rectangular core plates that are stacked;
• a plurality of plate oil flow passages and a plurality of plate coolant flow passages alternatingly formed between the plurality of the core plates;
• a plurality of rectangular fin plates each disposed at one or more flow passages of the plurality of the plate oil flow passages or the plate coolant flow passages;
• the core plates each including a pair of oil holes and a pair of coolant holes;
• in a case where a first reference line and a second reference line are defined as lines which pass through a center of one of the fin plates, and which are perpendicular to each other in a plane of each of the core plates, each of the fin plates have anisotropy such that a passage resistance in a direction parallel to the first reference line is smaller than a passage resistance parallel to the second reference line,
• the pair of the oil holes being positioned on an outer edge of one of the core plates, the pair of the oil holes being positioned at symmetrical positions with respect to a center of the one of the core plates to sandwich the center of the one of the core plates, and the pair of the oil holes being positioned to sandwich one of the fin plates along the first reference line, and
• the pair of the coolant holes being positioned on the outer edge of the one of the core plates, the pair of the coolant holes being positioned at symmetrical positions with respect to the center of the one of the core plates to sandwich the center of the one of the core plates, and the pair of the coolant holes being positioned to sandwich the one of the fin plates along the first reference line,
• wherein the pair of the oil holes are positioned on a diagonal line of one of the core plates, and the pair of the coolant holes are positioned on a diagonal line of the one of the core plates which is different from the diagonal line on which the pair of the oil holes are formed, and
• wherein at least one flow passage of the plurality of plate oil flow passages or the plurality of plate coolant flow passages is formed having a length and a width, such that the one of the fin plates extends along an entirety of the width of the at least one flow passage but only along a portion of the length of the at least one flow passage, so as to occupy only part of the at least one flow passage between the pair of oil holes or the pair of coolant holes.