Update Sept. 26, 2026: After my inspection, I checked directly with GM. The company confirmed to me that its new full-size trucks have wax-coated frames. I put my camera underneath a light-duty truck at the Texas State Fair, then checked a heavy-duty truck. I found wax on both, consistent with GM’s confirmation.
The big takeaway from this walk-around is straightforward: I found wax on the display trucks I inspected. If you were expecting the new trucks at the show to have an entirely different-looking frame finish, that is not what I saw underneath them.
What I saw under the light-duty truck
I started by looking along the frame of the light-duty truck. The coating was visible as I moved the camera underneath, and I described it in the video as the same kind of wax finish I had seen before. I also moved the camera farther under the truck to show the surrounding hardware, including the exhaust, rear axle, shocks and suspension.
That gives you a closer view than an exterior walk-around can provide. The new bodywork and interior may draw the crowd, but I know some of you want to see what is underneath before you get excited about ordering a truck.
The heavy-duty truck had a similar feel
On the heavy-duty truck, I touched the frame coating and could lift material with my fingers. I checked my fingertip on camera and identified the material as wax. That was the useful part of getting underneath these trucks in person: I could show you what I was seeing and what it felt like, rather than guessing from a polished display photo.
These new GM full-size trucks have wax-coated frames. I found wax on the light-duty and heavy-duty trucks at the Texas State Fair, and GM confirmed the continued use of wax when I followed up. That settles the question of whether these new full-size trucks have abandoned wax: they have not. My inspection and GM’s confirmation of wax do not, by themselves, describe every treatment that may be present beneath it.
Why GM’s wax coating remains controversial
The debate is about whether that protective layer stays in place. Owners have reported wax separating from the frame, with corrosion showing where the coating is missing. GM has documented that condition in service bulletin 19-NA-255. The January 2024 revision includes Silverado and Sierra 1500 models as well as 2500HD and 3500HD trucks. It identifies inadequate surface preparation by the frame supplier as a possible cause and provides a procedure for repairing affected areas.
That is evidence of a recognized problem on some trucks, not proof that every wax-coated frame will fail. The bulletin also is not a recall or a durability verdict on the new trucks I inspected today. But it explains why owners want more than a clean-looking frame at an auto show.
GM’s midsize trucks take a different approach
GM’s HD trucks have used wax-coated frames for years, alongside the full-size light-duty pickups. Finding wax on the HD truck today is a continuation of that practice, not a newly introduced change. The Colorado and Canyon are the midsize exceptions, with the e-coated, painted finish discussed in our earlier reporting. In my April 2023 report on the Colorado’s painted frame, Chevrolet confirmed paint rather than wax, and GMC confirmed the same for Canyon.
I asked GMC’s Patrick Sullivan why the company used different coatings. He attributed the choice to decisions made while developing each truck architecture.
“Both solutions – waxed coating for Sierra and painted coating for the Canyon – meet our high standards for corrosion.”
That was GM’s response in 2023. Engineers had also told me that wax could flow back across small scratches. That explanation helps describe the intended advantage; it does not answer an owner whose coating has peeled away.
E-coating uses an electrical process to deposit a protective paint film on metal. Other automakers use it, too: Ford’s F-150 frame-repair instructions explicitly identify e-coat on the frame, and Stellantis confirmed its use on underbody components in our earlier rust reporting. These are documented examples, rather than a claim that every component on every competing truck receives an identical treatment.
That is why GM’s split approach keeps raising questions. It already uses a painted finish on its midsize trucks, while the full-size and HD frames I inspected still had wax. The useful comparison is how well the complete coating system holds up over time, including adhesion and coverage, rather than assuming either material makes a frame immune to corrosion.
GM confirmed to me that the new full-size trucks still have wax-coated frames. That contradicts the earlier report that the 2027 light-duty trucks would move away from wax entirely. Whether GM also changed a treatment beneath the wax, and how the frames will hold up after years of road salt, weather and use, are separate questions. I have not done that long-term test on these trucks.
I will keep digging into the details as I get more time with the new trucks. For now, the video gives you a direct look at the frame finish I found in Texas, including the heavy-duty coating that came away on my finger.
