2008 Chevy Silverado 4x4 5.3 Ran it too long without oil change, now it has a rattling sound that gets louder as you give it gas.

Hi,
your description is a bit generic. No mention of mileage covered and no mention of miles covered between the prior and the "late' oil change. However, based on your statement, I would venture to say that your engine and rod bearings are now a problem. Should I be correct, further operation of the vehicle will result in crankshaft damage,, and possible engine siezure.

If the rattle you describe is "light' but becomes "heavy" as you give it gas, then it's the mains that have gone. If it's light, and just rattles with more intensity when you give it gas, then it's the rod bearings that have gone.

I would love to be proven wrong::))