Lawsuit Claims Certain Cadillac, Chevy, GMC Vehicles’ Fuel Economy Has Been Affected by General Motors V-8 Engine Recall Fix

Owners were asked to use higher-viscosity motor oil as part of a solution for the defective 6.2-liter V-8 engines, potentially affecting their vehicle’s fuel efficiency.

A recently filed class action lawsuit claims that General Motors’ (GM) remedy for a major engine defect could force nearly 600,000 vehicle owners to sacrifice fuel efficiency in order to avoid catastrophic engine failure.

The complaint (PDF) was filed in the U.S. District Court for the Eastern District of California on May 12, presenting claims for seven different plaintiffs from six states, each of whom own or lease 2021 through 2024 GM vehicles that are equipped with the 6.2-liter L87 V8 engine, which have now been recalled due to manufacturing defects. 

The GM V-8 engine recall was announced on April 24, impacting nearly 600,000 popular GM models, including the Chevy Silverado 1500, Suburban, and Tahoe, as well as the GMC Sierra 1500, Yukon, and Yukon XL, and the Cadillac Escalade and Escalade ESV. The recall was prompted by more than 28,000 field complaints, over 14,000 of which involved complete loss of propulsion due to engine component defects.

The failures have been linked to engine defects affecting rod bearings and crankshaft components, critical parts responsible for keeping the engine running smoothly. If these parts fail, the engine can seize, causing significant engine damage and dramatically increasing the risk of an accident.

According to the complaint, GM’s recall fix does not repair or replace most of the affected engines. Instead, for vehicles that pass a basic inspection, the company is requiring a switch to thicker 0W-40 motor oil, replacing the originally recommended 0W-20 oil. GM claims this change may offer better protection against engine failure, but plaintiffs argue it comes with a hidden cost.

The lawsuit maintains that thicker oil increases internal resistance and reduces engine efficiency, resulting in higher fuel consumption. The complaint cites industry research showing that the required oil change could reduce fuel economy by 3% to 4%, or even more in engines that rely on GM’s Dynamic Fuel Management technology, which is designed to save fuel by deactivating cylinders at cruising speeds.

For owners, that could mean spending hundreds of dollars more on gas over the life of the vehicle. The lawsuit estimates that a typical Cadillac Escalade driver may be forced to buy an additional 240 gallons of premium gasoline over 120,000 miles, costing nearly $1,000 more than expected.

“To fix an engine defect of its own making, Defendant General Motors LLC (‘GM’) has cast the owners of some 600,000 trucks and SUVs out of the frying pan and into the fire,” the lawsuit says. “Thicker oil may (or may not) help mitigate the Engine Defect, but it will also materially decrease fuel economy and require owners to purchase hundreds of extra gallons of gasoline over their vehicles’ lifespans.”

Each plaintiff says they purchased their vehicle based partly on fuel economy and reliability claims made by GM. Had they known about the defect, or that the recall solution would reduce efficiency, they claim they would have paid less or chosen a different vehicle.

The lawsuit raises multiple claims, including fraud by concealment, unjust enrichment and breach of warranty. Plaintiffs are seeking class action certification, restitution and compensation for economic losses, including the diminished value of their vehicles and increased fuel costs.