Class Action Lawsuit Claims 2024-2027 Chevy Silverado, GMC Sierra Diesel Models Plagued by Engine Oil Cooling System Defect

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General Motors faces a proposed class action lawsuit that alleges the engine oil cooling system in 2024-2027 model year Chevy Silverado and GMC Sierra trucks equipped with 6.6-liter L5P Duramax diesel engines is defective in that it is prone to crack or otherwise fail during normal operation. 

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The 107-page lawsuit against GM says that when the apparent defect manifests, pressurized engine oil can escape through the cooler and enter the engine cooling system and/or leak outside the vehicle. This can rapidly deplete an engine’s supply of lubricating oil, contaminate the engine and cooling systems and their components, deprive critical engine components of necessary lubrication, and cause overheating, loss of engine power, engine seizure, and sudden, catastrophic engine failure, the complaint states. 

The class action lawsuit explains that the engine oil cooling system is designed to use engine coolant, which circulates through an engine oil cooler, to remove heat from and regulate the temperature of an engine’s lubricating oil while keeping the oil and coolant separate. According to the lawsuit, the GM cooling system problem stems from the engine oil cooler’s inability to withstand the pressures, temperatures, thermal cycling, vibration and other forces that occur during ordinary, expected vehicle operation. 

The filing mentions that the Silverado and Sierra cooling system issue is so pervasive that replacement parts are on a national backorder with months-long waiting periods, leaving many drivers without a functioning vehicle.

The case accuses the automaker of refusing to repair vehicles under warranty due to “insufficient oil maintenance,” with GM often covering only the cost of oil cooler replacements and flushes when, in fact, full engine replacement is necessary. Even when replacement parts are covered under warranty, the suit continues, GM will replace faulty engine oil cooling system components with “equally defective replacement parts,” leaving an affected vehicle susceptible to repeated failure.

According to the lawsuit, the out-of-pocket costs of addressing the engine oil cooling system problem can run Silverado and Sierra drivers tens of thousands of dollars. 

“Moreover, because replacement GM oil coolers and related components have been subject to lengthy backorders, Class Members may be left without the use of their Vehicles for extended periods or forced to purchase aftermarket replacement parts when GM parts are unavailable,” the filing stresses. 

General Motors has allegedly known of the engine oil cooling system defect since at least August 2024, when it issued to dealers a service bulletin pertaining to “possible engine coolant contamination,” and potentially as early as November 2023, when GM customer service responded to an online complaint about the issue. Nevertheless, the automaker has failed to disclose and “actively concealed” the problem from the public while touting the Silverado and Sierra models at issue as reliable and durable, the suit claims. 

“GM has been plagued with customer complaints concerning premature failure of the Oil Coolant System in Class Vehicles as a direct result of the Defect yet has done nothing to protect the significant investment Class Members made in these Vehicles,” the complaint reads. 

The class action lawsuit looks to cover all individuals or entities in the United States that bought or leased a 2024-2026 Chevrolet Silverado 2500HD or 3500HD or GMC Sierra 2500HD or 3500HD vehicle equipped with the 6.6-liter L5P Duramax Turbo-Diesel V8 engine (or a 2027 model equipped with the same or a similar engine oil cooler assembly) for purposes other than resale. 

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