Automotive
For more than a decade, GM truck owners have watched oil viscosity get thinner and thinner, mostly in the name of squeezing out small fuel economy gains. Now the mood is shifting hard in the other direction. A recent GM Authority reader poll centered on the upcoming next-generation Small Block V8 shows most enthusiasts want GM to move back to thicker oil, with 5W-30 leading the votes and 0W-40 right behind it. Only a small slice of respondents wanted to keep the current 0W-20 spec, which says a lot about where owner confidence is at right now.
It is easy to understand why this debate has become so personal for truck people. GM moved its full-size truck V8s to 0W-20 around the 2020s era to help meet CAFE targets, and the official reasoning has always been that modern engines are designed around tighter clearances and advanced oil formulas. On paper, that checks out. But truck life is not a lab test. Towing, heat, long highway pulls, and heavy throttle under load are exactly the conditions where owners worry a thinner oil film has less margin for error, especially once miles stack up and wear tolerances inevitably open a bit.
The flashpoint was the L87 6.2L V8 recall that hit a huge number of GM’s most popular trucks and SUVs, including Silverado, Sierra, Tahoe, Suburban, Yukon, and Escalade models. Reporting around the recall points to internal engine failures tied to rotating assembly problems, and the remedy for vehicles that pass inspection has drawn the most attention: GM’s guidance includes switching to a higher-viscosity 0W-40 oil along with related service parts. That move has fueled the exact argument enthusiasts have been making for years, that a thicker oil can provide extra protection when temperatures climb and loads stay high. At the same time, it has created a weird split where some owners are told 0W-40 is the safer play, while others are warned their warranty depends on sticking with 0W-20.
Looking ahead, GM’s Gen 6 Small Block V8 decision is about more than just an oil cap label. It is about whether GM prioritizes the last fraction of a mpg on a test cycle or builds in the kind of durability confidence truck buyers expect when they are hauling and towing for years. The timing is interesting, too, because proposed federal changes could ease some of the pressure that pushed automakers toward ultra-thin oils in the first place. And GM already proves it understands thicker oil in demanding applications, with factory specs on modern Corvettes that call for heavier viscosities under the dexosR performance umbrella. If GM wants the next truck V8 to feel like a long-term keeper, listening to the people who actually work these engines might be the simplest win of all.
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Mike Floyd is a finance executive by trade and a car enthusiast at heart. As a CFO with a keen eye for detail and strategy, Mike brings his analytical mindset to the automotive world, uncovering fresh insights and unique perspectives that go beyond the surface. His passion for cars—especially his favorite, the Porsche 911, fuels his contributions to Automotive Addicts, where he blends a love for performance and design with his professional precision. Whether he’s breaking down industry trends or spotlighting emerging innovations, Mike helps keep the site both sharp and forward-thinking.
