GM Owners Want Thicker Oil in Next-Gen V8: Here’s Why – Jalopnik

For more than a decade, General Motors has focused heavily on efficiency-oriented engine technologies in its V8 lineup. From model year 2014 onwards, cylinder deactivation features and ultra-light oils such as 0W-20 became standard. On paper, this approach worked well. Power increased and fuel consumption improved. At the same time, however, owners’ and enthusiasts’ confidence in the long-term reliability of these engines waned.

Those concerns came to a head with the 6.2 liter L87 V8. Nearly 600,000 trucks and SUVs from model years 2021 through 2024 were recalled after GM identified connecting rod defects related to lubrication problems. The thinner oil could not maintain its strength under high loads and temperatures. The result, according to critics and lawsuits, was metal-on-metal contact that led to catastrophic engine failure.

GM’s response was telling. For recalled engines that pass inspection, the solution is not a redesigned bearing or a revised oil system, but thicker 0W-40 oil and a new oil filter. That change alone has fueled the debate, as many GM V8 owners no longer believe thin oil is worth the risk.

Polling conducted by GM Authority asked readers what they thought would be the type of oil used in future GM models. The results show that a large majority of readers pointed out that the brand used heavier oil in its next generation small block V8 engines. The current oil used, 0W-20, received minimal support. The majority of readers surveyed supported 0W-40 or even a return to 5W-30, which was used in older trucks until 2013.

Some believe that the technical choices around thinner oil come not from real-world use, but from the efficiency of the test cycle. Large trucks are often used for towing and extended highway driving, conditions that place higher demands on engine lubrication. For years, enthusiasts were told that modern engines were specifically designed for low-viscosity oil. Now, in the wake of widespread failures, GM itself is mandating thicker oil as a corrective measure. At the same time, some owners are suing GM, claiming the switch to 0W-40 increases fuel economy and decreases vehicle value. The debate has in fact been turned around.

The oil strategy that GM developed was built around regulatory pressures such as the Corporate Average Fuel Economy standards. Models could achieve small but meaningful improvements in efficiency by using low-viscosity oil, which is why many modern engines use them in the first place. However, recent changes in federal fuel economy rules have eased that pressure. Without the threat of fines hanging over them, manufacturers can now afford to prioritize sustainability, especially as fleet targets have been reduced and incentives for technology such as stop-start have been withdrawn.

Sales data complicates the story. Despite reliability concerns, Silverado and Sierra sales increased significantly after the introduction of these new V8 technologies in 2014 and remained strong with the adoption of additional technologies such as Dynamic Fuel Management. Performance improved, fuel economy increased and buyers kept showing up. Looking ahead to GM’s Gen 6 small-block V8s (on which the company spent nearly a billion dollars) expected to debut in the Silverado and Sierra in 2027, the oil issue has become symbolic. It represents a broader choice between pursuing increasing efficiency or restoring confidence in the engine’s long-term durability, and owners have made their preference clear.