At Least Two More Class Actions Say GM’s Gen. IV Vortec 5300 Engines Are Defective

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General Motors faces at least two more proposed class action lawsuits over the “inherently defective” Generation IV 5.3 Liter V8 Vortec 5300 LC engines found in certain 2011-2014 vehicle models. 

According to the cases, the engines, which are an available option for the following vehicle models, were “engineered to fail,” and consume abnormal amounts of oil far in excess of reasonable industry standards: 

• Chevrolet Avalanche;
• Chevrolet Silverado;
• Chevrolet Suburban;
• Chevrolet Tahoe;
• GMC Sierra;
• GMC Yukon; and
• GMC Yukon XL.

For its part, General Motors has long known of yet failed to disclose the truth about the oil consumption problems plaguing the above-listed vehicles, and has offered only stop-gap remedies in place of a proper repair of the defect, the lawsuits allege. The suits share that the oil consumption problem has been the subject of “an extraordinary number of complaints” dating back to 2007 GM vehicle models.  

“Despite this knowledge, GM continued selling and leasing Class Vehicles without ever disclosing the Oil Consumption Defect,” the suits charge. “Indeed, GM has never disclosed the Oil Consumption Defect to consumers.” 

As a result of their excessive oil consumption, the Vortec 5300 engines suffer from low oil levels, insufficient lubricity and corresponding internal damage, the similarly worded lawsuits say. 

The suits place blame for the Vortec 5300 oil consumption problems on a combination of multiple factors. The primary cause, the cases state, is that the piston rings installed in the engines by GM fail at keeping oil inside of the crankcase. Another culprit, the lawsuits say, is the vehicles’ Active Fuel Management (AFM) system, which converts the engines from eight- to four-cylinder operation during light-duty driving. From the complaints:

“The AFM system comprises an oil pressure relieve valve that sprays oil directly at the piston skirts. This oil spray overloads and fouls the defective piston rings, triggering oil migration past the rings. The migrating oil either burns or accumulates as carbon buildup on the combustion chamber’s surfaces. Separately, when in four-cylinder mode, the lack of combustion in the four inactive cylinders invites excessive oil migration into the combustion chambers. Combustion controls upward oil migration by providing an opposing force and by assisting piston ring sealing, and when it’s absent the oil consumption accelerates.” 

Moreover, the Generation IV Vortec 5300 is hampered by a flawed PCV system that, according to the suits, vacuums atomized oil from a vehicle’s valvetrain into its intake system, where it ends up burned in the combustion chambers. This process only adds to cars’ excessive oil consumption, the cases claim. Further exacerbating the oil-burning problem and related engine damage concerns is GM’s implementation of a defective oil life monitoring system, which wholly fails to advise drivers when their engine oil levels are critically low, the lawsuits state: 

“Despite its name, GM’s Oil Life Monitoring System does not monitor oil level. Rather, it monitors engine conditions, such as revolutions and temperature, to calculate the expected deterioration in oil quality and thus the time for a recommended oil change. The Oil Life Monitoring System’s adaptive change intervals do not take oil level into account. The result is a system that directs drivers to travel thousands of miles with inadequate engine lubricity levels, wearing out and damaging moving internal engine components – a particularly serious problem in light of the fact that the Oil Consumption Defect causes improper and excessive oil loss in each of the Class Vehicles.”

Compounding matters even further are dashboard oil pressure gauges and oil canister images that, in reality, provide no indication as to when the oil pressure in a class vehicle falls low enough to damage internally lubricated engine parts or cause engine failure, according to the suits. Even if GM’s warning system worked, it would still do nothing to prevent the “full scope of the harms” caused by the oil consumption defect, the plaintiffs allege.

Still further, an ancillary side effect of the apparent oil consumption problem is the fouling of an engine’s spark plugs due to oil migration, per the cases. A fouled spark plug can produce an “anemic/weak spark,” an intermittent spark and/or no spark at all, leading to engine misfires and shutdowns that place drivers and passengers at risk, the suits say. 

In place of a true repair, GM has allegedly instructed dealers over the years to address the oil consumption issue with “stop-gap fixes” of the Vortec 5300 engine’s PCV and AFM systems and decarbonization of combustion chambers and piston rings. These remedies, however, do not provide a complete and adequate fix of the oil consumption problem, the plaintiffs argue.

The plaintiffs and proposed class members each paid money to buy or lease a GM vehicle with a defective engine that’s responsible for a laundry list of related internal damage, the cases claim. The consumers were damaged financially in that they paid more money for their vehicles than they would have had they known of the Vortec 5300 oil consumption defect, the suits say. 

The complaints can be found below.

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