NHTSA Expands GM L87 Probe as 0W-40 Remedy Faces a Tighter Base-Oil Market
NHTSA is examining hundreds of engine failures following GM’s 2025 recall remedy at a time when Group III base oil remains under significant cost and supply pressure.
More than a year after General Motors took the unusual step of switching hundreds of thousands of recalled vehicles from SAE 0W-20 to dexos R SAE 0W-40, the remedy is back in the spotlight. The National Highway Traffic Safety Administration’s Office of Defects Investigation opened Engineering Analysis EA26005 on August 20, 2026, expanding its investigation of GM’s 6.2-liter L87 V8 engine to 997,743 vehicles from model years 2021 through 2026. The investigation includes Chevrolet Silverado 1500, Tahoe and Suburban; GMC Sierra 1500, Yukon and Yukon XL; and Cadillac Escalade and Escalade ESV vehicles. It follows a Recall Query opened earlier this year to assess the effectiveness of GM’s 2025 recall remedy.
According to the NHTSA Office of Defects Investigation opening resume for Engineering Analysis EA26005, ODI has received 499 complaints alleging engine failure after completion of the recall remedy. Of those, 473 involved vehicles that received the oil-viscosity change and 26 involved vehicles that received replacement engines. GM reported receiving 6,953 complaints of post-remedy engine failure. ODI has also received 191 reports of L87 engine failures involving engines produced after the production period covered by the original recall, bringing later-production and 2025-2026 model-year vehicles into the investigation.
The numbers do not establish that SAE 0W-40 caused the failures. But the investigation again draws attention to one of the more unusual aspects of the original recall: the use of a substantially higher-viscosity motor oil as part of the remedy for engines that were allowed to remain in service. And this time, the issue is resurfacing in a lubricant market that looks considerably different from the one GM faced when the recall was announced.
An Unusual Remedy
GM issued Recall 25V-274 in April 2025 for nearly 600,000 vehicles equipped with L87 engines produced during a suspect manufacturing period. GM attributed the problem to manufacturing and quality issues involving connecting rods and crankshafts. These included rod-bearing damage associated with sediment on connecting rods and crankshaft oil galleries, as well as crankshafts with dimensions or surface finishes outside specification. The conditions could result in bearing damage and, ultimately, catastrophic engine failure.
The recall remedy took two paths. Engines that failed GM’s inspection procedure were repaired or replaced, while vehicles that passed received an oil and filter change and were permanently switched from the previously specified dexos1 SAE 0W-20 to dexos R SAE 0W-40. The oil-fill cap was also replaced to reflect the new viscosity requirement. That viscosity change immediately caught JobbersWorld’s attention.
In May 2025, JobbersWorld reported in “GM Recall Sparks Supply Chain Concerns Following Sudden Switch to dexos R SAE 0W-40” that moving such a large vehicle population from one of the most widely used passenger-car motor-oil grades in the United States to the much more specialized dexos R SAE 0W-40 could create an immediate supply challenge. Mobil 1 Supercar 0W-40 was initially specified for the recall, and the available supply base for dexos R SAE 0W-40 was considerably narrower than that for dexos1 SAE 0W-20. JobbersWorld estimated at the time that the initial recall could shift roughly 570,000 gallons of motor-oil demand from 0W-20 to 0W-40 during the remainder of 2025.
GM subsequently acknowledged potential availability constraints. Later that year, GM announced Mobil 1 FS 0W-40 dexos R as a more competitively priced option for oil changes following the initial recall service and noted that occasional shortages could occur as production and distribution ramped up. The change was also reflected in a later revision of the recall bulletin. The dexos R 0W-40 supply base has since broadened, though it remains concentrated among a relatively small group of marketers and is still far narrower than the dexos1 SAE 0W-20 market.
Now the Question Is Different
In spring 2025, the immediate lubricant-industry question was whether enough approved 0W-40 could be moved through the supply chain quickly enough to support the recall. Today, the question is more fundamental: What role was the higher-viscosity oil expected to play in protecting engines potentially exposed to the manufacturing defect, and was the combination of inspection and lubricant change sufficient?
The continuing failures should not be interpreted as evidence that SAE 0W-20 caused the original problem. GM identified manufacturing and quality issues involving connecting rods and crankshafts as the underlying concern. Likewise, the 473 complaints involving vehicles that received the viscosity-change remedy do not by themselves demonstrate that SAE 0W-40 failed as a lubricant. Those engines were already part of a population potentially exposed to the manufacturing problem and remained in service because they passed GM’s inspection.
NHTSA is now examining whether the remedy adequately addressed the risk of subsequent failure. Reports involving replacement engines and engines produced after the original recall period also raise broader questions that extend beyond the viscosity change itself. Even so, the use of lubricant viscosity as part of the original remedy remains noteworthy.
Automakers routinely introduce new viscosity grades as engine designs, emissions requirements and fuel-economy targets evolve. It is far less common to permanently move hundreds of thousands of vehicles already in service from SAE 0W-20 to SAE 0W-40 as part of a safety recall addressing a mechanical manufacturing defect.
The Lubricant Market Has Changed Dramatically
There is another significant difference between May 2025 and today: the cost and availability of the premium base stocks used in high-performance synthetic motor oils. JobbersWorld reported in late July that Group III base-oil cost increases varied considerably depending on supplier, geography and contract coverage. Blenders with stronger Gulf Coast contract positions reported increases in the mid-single digits per gallon, while those relying on East Coast, Canadian or supplemental supply faced increases approaching $8 per gallon.
The increases reflected an exceptionally tight Group III market following disruptions to Middle Eastern supply, reduced availability of imported material and limited flexibility in sourcing approved premium base stocks. Those pressures have been working their way into finished lubricants, with JobbersWorld’s tracking of the 2026 lubricant pricing cycle showing full-synthetic lubricant price increases generally reaching approximately $7.50 to $8.50 per gallon, depending on supplier and product.
The significance to the GM situation, however, goes beyond price. High-performance OEM-approved motor oils depend on specific combinations of base stocks, additives, viscosity characteristics and approved formulations. In a constrained market, base oil may be available, but not necessarily the right oil in the right grade with the right approval. JobbersWorld highlighted that issue in July when examining how the continuing shift toward lower-viscosity passenger-car motor oils is increasing the industry’s dependence on higher-quality base stocks. As viscosity requirements become more demanding and OEM approvals more specific, formulation flexibility narrows.
The GM recall presents an interesting variation on that trend. GM moved in the opposite viscosity direction, taking affected L87 engines from SAE 0W-20 to SAE 0W-40. But that did not necessarily remove the vehicles from premium-base-oil exposure. Instead, it moved them into a relatively narrow, high-performance dexos R product category.
This does not mean dexos R SAE 0W-40 depends exclusively on Group III. Depending on formulation and approval, these oils can incorporate Group III, Group III+, PAO and other components. But the cost and supply environment surrounding premium base stocks is considerably more difficult today than it was when GM announced the recall in spring 2025.
A One-Time Recall Became Recurring Demand
There is another aspect of the original viscosity change that is easy to overlook: it was permanent.
GM did not instruct owners to use SAE 0W-40 only during the recall service. Vehicles receiving the remedy had their oil-fill caps changed and their future oil recommendation revised. In effect, those vehicles became recurring dexos R SAE 0W-40 consumers. That means the lubricant demand created by the recall did not disappear when dealers completed the initial oil changes; every subsequent oil change continues to generate demand for the more specialized product.
Relative to the total U.S. PCMO market, the incremental volume is small. Within the much narrower dexos R SAE 0W-40 segment, however, the recurring demand is considerably more meaningful. And those recurring gallons are now being supplied in a market where premium base-oil costs are substantially higher and supply flexibility is more limited.
What Happens Next Matters
NHTSA’s Engineering Analysis remains open, and it is too early to know what additional action, if any, will result. But the possible outcomes have different implications for lubricant suppliers.
If the existing remedy remains unchanged, vehicles already converted to SAE 0W-40 will continue generating recurring demand for dexos R oil. If the population receiving the viscosity remedy is expanded, additional 0W-40 demand could enter the market while premium base-stock costs remain elevated.
If investigators conclude that the existing inspection and oil-change remedy is insufficient and additional engine replacements are required, the lubricant-volume impact could be smaller, while the financial burden shifts increasingly toward hardware. And if another lubricant-related service action emerges, it will have to be supplied under market conditions significantly more difficult than those prevailing when the recall began.
That is what makes the latest development particularly noteworthy for the lubricant industry. When JobbersWorld first reported on the L87 recall in May 2025, the concern was whether an abrupt shift of hundreds of thousands of vehicles from SAE 0W-20 to dexos R SAE 0W-40 could be accommodated without disrupting supply. More than a year later, the dexos R supply base has broadened, but the broader premium-base-oil market has become substantially more expensive and supply-sensitive.
Against that backdrop, NHTSA is investigating engine failures occurring after the original remedy was performed. The story that began with connecting rods and crankshafts became a motor-oil supply story when GM turned to 0W-40 as part of the remedy. The Engineering Analysis remains open, and its ultimate findings and any resulting actions are yet to be determined. What happens next could provide an important test not only of the remedy, but of the lubricant supply chain’s ability to respond if GM is again required to change course.
Sources:
- General Motors Service Bulletin 25-NA-339, November 2025: Mobil 1 FS 0W-40 dexos R availability and pricing guidance
- General Motors Recall Bulletin N252494000-10, January 20, 2026: Updated L87 recall service guidance
Editor’s Note: This article is based on publicly available NHTSA Office of Defects Investigation documents, including the opening resume for Engineering Analysis EA26005 and materials associated with Recall 25V-274, together with JobbersWorld’s reporting and tracking of lubricant-market conditions as of August 2026. NHTSA’s investigation remains open, and complaint counts cited in this article do not establish causation between the SAE 0W-40 viscosity change, any other element of the recall remedy, and subsequent engine failures.
Analysis concerning lubricant supply, Group III base-oil availability and pricing, and potential market implications reflects JobbersWorld/Petroleum Trends International analysis and is provided for informational purposes. Readers should consult official NHTSA and General Motors sources for current recall and vehicle-specific information.