The real problem with the stock Duramax pan isn’t just cooling. It’s drainage. The inward-protruding weld nut keeps a pool of contaminated oil trapped in the sump, and because the pickup tube sits in that oil, it can hold dirty oil too. That means every oil change starts with old oil, soot, oxidation, aeration, and debris still in the system. Our Banks CoolRunner Oil Pan fixes that by putting the magnetic drain plug at the lowest point so the sump drains completely. Once that trapped pool is gone, the pickup tube can drain as well instead of staying submerged. From there, we built the pan to do the rest of the job right: die-cast aluminum construction, aligned Flow-Thru Fins®® to move heat out of the oil, an anti-cavitation dimple under the pickup, a full-length squeeze gap for controlled RTV sealing, and a sensor port for added temperature monitoring. Cleaner oil changes, better oil control, and stronger heat rejection all start with getting the old oil out.
The video begins with Banks' effort to improve fluid cooling across the Duramax platform, including the rear differential cover, transmission pan, oil pan, and oil cooler. Although the Duramax oil cooler has evolved over the years, the oil pan has largely remained a stamped-steel design. Banks argues that this matters because higher engine output creates more heat, and excessive oil temperature degrades the oil. When oil temperature rises too far, the ECM reduces fueling to protect the engine, which cuts power precisely when the truck may need it most, such as while towing at altitude. The stated goal of the project was to reduce oil temperature so the engine can sustain maximum power for longer periods.
During development, Banks says it found a more serious issue than cooling alone: a quantity of dirty oil that remains trapped in the engine even after a normal oil change. The claim is based on the Duramax 6.6L L5P's fill quantities. The factory fill is 11 quarts, but a routine oil change calls for only 10 quarts. According to the demonstration, the missing quart remains trapped in the oil pan sump and pickup area.
Using a 2020 Silverado equipped with the 6.6L L5P, the team first verified that the oil level was correct on the dipstick. They then drained the oil conventionally, reinstalled the drain plug, and removed the pan to inspect what remained. Inside the stock pan, a substantial pool of oil was still present. Banks attributes this to the drain-plug weld nut, which protrudes roughly three-quarters of an inch into the pan. Because of that internal obstruction, approximately three-quarters of an inch of oil remains below the effective drain level. The problem is compounded by the pickup tube, which stays submerged in that captive oil, leaving additional oil trapped inside the tube itself.
Banks characterizes the trapped oil as permanently contaminated oil that never leaves the engine during normal service. The concern is not just the volume, but the condition of that residual oil. The video describes it as containing metal debris, soot, oxidation products, and aerated oil. According to the explanation, this leftover oil is harmful to cylinder linings, bearing surfaces, and, more broadly, the entire engine lubrication system.
The engineering concern is straightforward: every oil change mixes fresh oil with a quart of old oil that could not be drained. That means the engine never receives a truly complete oil change as long as the stock pan remains in place. Banks presents this as a built-in contamination source rather than a minor service inconvenience.
To prove the point visually, Banks 3D-scanned the stock pan and produced an exact duplicate in clear plastic. The transparent pan was installed on the engine, filled to the proper level, and used to observe oil behavior during operation and draining. With the clear pan in place, the team could see the pickup tube, the mid-pan structure, and the stock dimple geometry.
Once the engine was started, the oil level visibly changed from its static condition to its dynamic operating condition as oil circulated through the engine. The demonstration showed fresh oil mixing with residual oil in real time. After the oil had fully circulated, the engine was shut down and the pan was drained just as before. The clear pan made the result obvious: a trapped pool of oil remained in the sump after draining.
The test also highlighted what happens in the pickup tube. Banks explains that even with the engine off, the oil pump can leave a low-pressure condition that keeps oil suspended in the tube, allowing the static oil level inside the pickup tube to remain higher than the visible oil level in the pan. When the pan was removed and the pickup tube broke free of the trapped oil, the footage showed oil rushing out as air entered to displace it. This confirmed that residual oil was trapped not only in the pan but also in the pickup tube.
Banks presents the CoolRunner oil pan as the solution to the trapped-oil problem. Unlike the stock pan, which uses the protruding weld nut and leaves roughly an inch of dirty oil behind, the CoolRunner places a magnetic drain plug at the lowest point of the pan. That layout is intended to let the pan drain completely.
Because the sump drains fully, the pickup tube is no longer left submerged in residual oil. Air can enter and displace the oil in the pickup tube as well, allowing that trapped oil to drain out completely. In Banks' framing, this eliminates the permanently retained quart of contaminated oil that remains with the stock pan. The CoolRunner also increases capacity by two quarts over stock. That added volume increases thermal mass, which slows heat saturation. Banks notes, however, that increased capacity alone does not solve oil-temperature problems indefinitely. Once all of the oil reaches operating temperature, it is still hot; the key is how effectively the system rejects heat.
The main heat-rejection strategy is the pan's fin structure. Banks says the fins on the CoolRunner are unusually long, thin, and closely spaced, to the point that the pan must be die-cast rather than sand-cast. According to the explanation, fins this deep and tall cannot be produced reliably with sand casting because the mold would break apart during removal. Banks also states that it avoids sand casting for lubrication components because residual sand can remain in the part, which is unacceptable in an oiling system.
Die casting also produces smoother internal walls, which Banks says improves drain-back to the pickup tube. In cross-section, the interior and exterior fins are aligned with one another in what Banks calls Flow-Thru Fins®. The idea is to create a direct thermal path from the hot oil inside the pan to the cooler ambient air outside. The video describes this as maximizing heat transfer efficiency.
Banks further compares the CoolRunner's external surface area with a competing PPE pan, stating that the CoolRunner provides 47% more external radiant surface area. The company also notes that the same Flow-Thru Fins® concept appears on its new Ram-Air transmission pans, with a separate technical discussion from Gale planned for another video.
Beyond cooling and drainage, the pan includes several details aimed at lubrication-system reliability. One is the sealing strategy. The stock pan uses a high-strength silicone adhesive, and as the bolts are tightened, the RTV forms a continuous bead. Banks emphasizes that silicone fragments must not break loose into the oil. To address this, the CoolRunner uses an OE-style full-length squeeze gap machined around the entire perimeter of the pan. Borrowed, as the video says, from decades of military development, this squeeze-gap feature is intended to control the RTV bead so that small strands do not shear off, fall into the sump, clog the pickup tube, and damage the engine.
The video points to the resulting RTV bead as uniform and continuous, without gaps or isolated nodules likely to detach. Another stock feature that Banks deliberately retained is the anti-cavitation dimple beneath the pickup screen. The company says this dimple is not cosmetic; it promotes laminar flow into the pickup tube and helps the pump draw in oil properly. Banks states that this feature is absent from other aftermarket pans, making it a notable part of the CoolRunner design.
The pan also includes provisions for monitoring and debris control. An 1/8-inch NPT port is built into the side of the pan for a temperature sensor, reflecting Banks' emphasis on instrumentation and data collection.
For the drain plug magnet, Banks specifies strontium ferrite. The video ties this choice to the Curie temperature, the point at which a magnetic material loses its magnetism. Referencing physicist Pierre Curie's late-1800s work, Banks explains that magnetic strength falls off at a critical temperature determined by the material. Strontium ferrite is used because it has a Curie temperature of 450° C and is highly resistant to corrosion. In practical terms, that makes it suitable for a magnetic drain plug operating in a hot, contaminated oil environment.
The recap closes with Banks' conclusion that the stock Duramax oil pan has two major shortcomings: it traps approximately a quart of dirty oil that cannot be removed during normal service, and it offers limited heat-rejection capability compared with a purpose-built cast pan. The CoolRunner is presented as a redesign intended to solve both issues through complete drainage, increased capacity, die-cast Flow-Thru Fins®, controlled RTV sealing, retention of the anti-cavitation dimple, sensor provision, and a high-temperature magnetic drain plug.
The engineering story is presented in a clear sequence: identify the thermal limitation, discover the trapped-oil issue, validate it with teardown and a transparent test pan, and then redesign the pan to improve both serviceability and cooling performance.
