Burnt oil is not normal. Even if the fluid is still reddish doesn't mean it's still doing its job. That's why I change mine every 25-30k instead of 50k like the manual says, esp. If your running a "chip" or running larger tires or towing a lot
Ok...see gmc place said its normal wear along with shavings! Ive also been told an injector could do it. I dnt knw who knws what and who just thinks they do. Been told its fine its the chip or tune or whatever u want to call it. Im just trying to get a real answer