Oil comsumption 2008 sierra - 2008 GMC Sierra 1500 2WD

the most likely cause is a crack in the oil cooler in the radiator

Sounds like you are triggering the check engine light due to low oil pressure. I would check your oil level and see if you are ok with oil. If you are then go to the nearest parts store and have them run a diagnostics (free) and tell you what the code is reading. That way you know what is going on. I have a feeling though that your oil pump is going bad and you are going to need a new oil pump

5w 30 is a common GM recommended oil - it has a wider ambient temperature range than (for example) 10w 30. The recommended grade is sometimes moulded into the oil filler cap that fits into the valve cover.

what oil you want to drain? if engine oil, its @ the oil pan

Sure, the only issue is oil comsumption. If you put the oil in and start to consume too much oil, consider HIGH MILEAGE Blend. These oils are both synthetic and regular oil. Casteroil and others make this oil.

The oil plug will be located on your oil pan. If you checked ther are you sure you checked all areas? I have never seen one anywhere else. Especially on an american made vehicle. I don't know your experience level but the oil pan is located just in front of the transmission under the engine. I hope that helps you find it.

Sounds like an oil pressure problem. The clacking sound is most likely the lifters are collapsing due to loss of oil pressure. You may have a failing oil pump.

Passenger side on the oil pan. Careful cause it comes out like a rocket! The oil filter is on the drivers side of the oil pan
GM p/n pf48

Where i s oil drain plug?
GMC 2008 Sierra

the oil consumption could be worn piston rings or the egr is clogged and forcing oil into the air intake but that new of a car its unlikely unless someone sugared the gas tank the sooty exhaust could be from the oil consumption