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.
This coolers massive 30% increase in cooling capacity makes it a great upgrade for 2001-2016 trucks. Some changes will be required to install on earlier trucks.
Trimming of Drivers Side Exhaust Manifold Heat Shield and Heat Shield Mounting Boss
Replace Original Elbow with Coolant Elbow 12675428 and Gaskets 12676826 / 97192667
Cooler Mounting Requires (3) M8-1.25x40mm Bolts and (2) M8-1.25x120mm Bolts
For a upgrade that require less modification, DHD uses the 2017-2019 Cooler Part Number 12678318. The 17-19 cooler fits with only minor hardware changes and still cools substantially better then the earlier coolers.