It wouldn’t bother me except these GM engines are well known for lifter failure and all sorts of other engine problems caused by AFM and DFM. In my last truck, also a 5.3, I started to have lifter issues around the 50k mark. I disabled the AFM and the issue went away.
After I did that, the mileage improved by 1 mpg. So it ended up being more fuel efficient without it.
My dads previous truck, 2008ish model, the engine cratered at just over 100k miles despite regular oil changes. Plus, I’ve known many people who have had the same issues with AFM engines.
You know what’s better for the environment ? Well maintained engines that run dependably for 100’s of thousands of miles. Not gimmicks that are designed purely for the EPA’s test cycle that don’t translate into real world savings.
