This study compared the performance of both baseline and enhanced traditionally built heat exchangers (aircraft oil coolers), to both baseline and enhanced additively manufactured (AM) heat exchangers of similar geometry. Three dimensional (3D) X-ray computed tomography scans were performed on the baseline traditionally built heat exchanger in order to develop a solid model for AM fabrication using a laser-based powder bed fusion process with AlSi10Mg powder. Two AM heat exchanger geometries were constructed to replicate the baseline traditionally built geometry, with one AM heat exchanger containing additional small air-side enhancement features. The air-side pressure drop for the AM heat exchangers was double that of the traditionally built baseline heat exchanger. Heat transfer was increased by about 10 percent for the baseline AM and by 14 percent for the enhanced AM heat exchanger when compared to the traditionally built baseline heat exchanger. Both of the AM heat exchangers performed as well as the enhanced traditionally built model, but both had a higher pressure drop. Ongoing research seeks to ascertain the specific causes of the increased pressure drop and improved heat transfer, in order to provide a foundation for enhancement of future AM-built heat exchanger designs.