This is a genuine GM OEM Duramax Diesel L5P Engine Oil Cooler Assembly.
The Duramax engine oil cooler is not normally a component that goes bad, however, it should be replaced after any catastrophic engine failure or during any performance engine builds.
The factory oil cooler has a stack plate design which makes cleaning any debris out nearly impossible. This is the reason we always recommend replacing the oil cooler. A defective engine oil cooler is also a major source for coolant/oil cross contamination. Check your coolant degas bottle for a layer of oil. If any appears, it is often defective oil cooler.
The 2017-2019 cooler serves as an excellent upgrade for your 2001-2016 Duramax trucks. These earlier L5P coolers offer increased cooling capacity, fit well without modifications, and utilize your original oil cooler to rear cover coolant elbow. At bare minimum, you will need fresh gaskets and (2) longer 100mm bolts to complete your install. See Below.