Valve Stem Seal Defect in 2021 Mazda Vehicles Linked to Excessive Oil Consumption, Class Action Claims

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A number of 2021 Mazda vehicle models contain defective valve stem seals that can allow oil to leak into the engine’s combustion chamber, a proposed class action claims. 

The 39-page lawsuit alleges that, as a result of the valve stem seal issue, 2021 Mazda CX-30, CX-5, CX-9, Mazda3 and Mazda6 vehicles consume an excessive amount of engine oil between regular oil changes. Per the suit, the problem poses a significant safety threat to drivers, passengers and pedestrians as it can lead to engine failure while the cars are being driven. 

According to the case, defendant Mazda Motor of America has “long known” of the valve stem seal issue yet concealed and “refused or otherwise [has] been unable to repair” the alleged defect under warranty. The complaint says that in an October 2021 dealer bulletin, the automaker recognized that the vehicle models at issue consumed high amounts of oil between oil changes and that “it is very likely that valve stem seal damage is causing oil to leak into the combustion chamber.” 

Instead of adequately remedying the valve stem seal problem, Mazda merely directs dealerships to “top off” a vehicle’s engine oil, the lawsuit says. To date, the automaker has offered drivers neither a suitable repair nor reimbursement for costs related to the valve stem seal defect, the case states. 

“Mazda has and will continue to benefit from its unlawful conduct – by selling more vehicles, at a higher price, and avoiding warranty obligations – while consumers are harmed at the point of sale, as their vehicles continue to suffer from the unremedied Valve Stem Seal Defect,” the lawsuit contends. 

Per the complaint, valve stem seals are supposed to prevent engine oil from contaminating the air/fuel mixture in a vehicle’s combustion chamber and prevent intake and exhaust gases from contaminating oil in the cylinder head and the rest of the engine. Importantly, valve stem seals are supposed to last for a vehicle’s lifetime, according to the case. 

The defect affecting the valve stem seals can cause not only excessive engine oil consumption but can also damage the engine and other components. From the complaint: 

“For instance, the defective valve stem seals in the Class Vehicles and the resulting engine oil burning in the vehicles’ combustion chambers creates carbon deposits on the valves and piston crown and contaminates the spark plugs, causing the cylinder to lose power. The Defect can also cause the engine valves to fail to seal, and in turn a lack of compression and a poor running engine. In addition, the defective valve stem seals can cause excess exhaust gases in the crankcase, which result in damage to other vehicle systems.” 

The lawsuit looks to represent consumers who are current or former owners or lessees of a 2021 Mazda CX-30, CX-5, CX-9, Mazda3 or Mazda 6 vehicle. 

The case was initially filed on April 19, 2022 in Orange County Superior Court before being removed to California’s Central District Court on May 25. 

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