In 2025, Consumer Reports reported how General Motors (GM) issued a safety recall affecting nearly 600,000 full-size trucks and SUVs equipped with the 6.2-liter L87 V8 engine. The investigation into GM’s recall of L87 vehicles has focused on potential manufacturing defects in the connecting rods and crankshafts that could cause complete engine damage or sudden engine failure. The recall covers various models from 2021 to 2024, including the Silverado 1500, Sierra 1500, Chevrolet Tahoe, Chevrolet Suburban, GMC Yukon and Cadillac Escalade.
Although GM originally specified 0W-20 oil for the engines, dealers were later instructed to switch to the thicker 0W-40 formula as part of the recall resolution. Naturally, the move sparked debate among car owners, who questioned whether ultra-low viscosity oil was suitable for high-output, 420-horsepower V8 engines. Many have questions about the effectiveness of this solution, especially since even the engines replaced in the recall have had recurring problems, according to AutoBlog.
This has resulted in more than 1,000 individual complaints, prompting the National Highway Traffic Safety Administration (NHTSA) to launch a remedial investigation in January 2026 to examine whether the recall actually addresses the real problem. Because of this, GM truck owners are now demanding thicker oil in future V8 engines. If thin fuel is indeed the culprit, then isn’t GM’s L87 doomed from the start?
Read More: The 5 Most Reliable Engines Ever in a Pickup Truck
GM L87 V8 connecting rod bearing and crankshaft issues
Close-up view of a GMC truck with a red GMC badge on the grille. – Jetcityimage/Getty Images
During an investigation of its L87 engines on its YouTube channel, technicians at Dave’s Auto Center said the problem may involve micromachining and lubrication behavior in the engine’s bottom end — the same mechanical area cited by plaintiffs in the class-action lawsuit against GM. To investigate the problem in detail, they dismantled two brand-new L87s. Their observations revealed that the crankshaft journal surface appeared “rigid or bumpy” rather than well polished, with one technician stating, “I’m looking for a mirror finish…but it doesn’t exactly look like a mirror finish.”
The team also highlighted the large chamfers on the connecting rod bearing surfaces, noting that “almost half of the bearings in this section are oil holes,” which could lead to oil film leakage. They further pointed out that material surface roughness may be the culprit, noting that if “your RZ [mean roughness depth] Six times your RA [roughness average]you start to lose control,” meaning small microscopic peaks and valleys can disrupt stable lubrication and cause problems.
According to Part 573 of NHTSA’s Recall Safety Recall Report on the L87, engine teardown analysis revealed two potential causes. Specifically, bearing damage can be related to deposits in the connecting rod and crankshaft oil passages. Additionally, the crank size and finish were found not to meet the specifications stated by the technicians. Although there is no official confirmation of what may be causing the problem, bearing failures are some of the most common problems with General Motors’ L87 V8 engines.
Would a thicker oil do the trick?
A mechanic wearing yellow gloves pours engine oil through a red funnel in a car engine. – Panya_photo/Shutterstock
When GM Authority asked readers what oil viscosity GM should use for its future V8 engines, only 16% voted for 0W-20, meaning most readers wanted to see a thicker solution. However, with these problems plaguing recalled engines equipped with heavier oil, it raises the question of whether replacing the engines would actually provide meaningful benefits. This is also evident in GM’s official recall notice, where the remedy is not just a switch to thicker oil, but also an engine inspection and engine replacement.
A study published in Tribology Reviews analyzing bearing failure noted that the purpose of lubrication is to separate surfaces and reduce wear. However, physical factors such as manufacturing defects are independent causes of bearing failure and cannot be prevented by lubrication alone. The NHTSA investigation, this study and independent expert mechanics all cited manufacturing defects as potential culprits, which heavy oil alone cannot completely eliminate.
Today, automakers use thinner oil to comply with stricter emissions standards and also because modern engines are better designed. Over time, the oil’s formula has improved. However, if the engine design is not precise and efficient enough, switching to leaner oil may do more harm than good. With GM engines still failing and the U.S. government wanting to know why, it looks like we’ll have to wait and see how the story ultimately unfolds.
Want to stay up to date on the latest tech and automotive trends? Sign up for our free newsletter to get the latest headlines, expert guidance and how-to tips, one email at a time. You can also add us as your preferred search source on Google.
Read the original article on SlashGear.
