I have a 2012 Chevy traverse with the 3.6L VVT engine. I was changing plugs yesterday and also cleaned the TB but when i removed the air intake tube that goes from the air filter box to throttle body had oil in it that was light colored. I checked the oil on the dip stick and it looked normal along with the oil change not too long ago. Also the antifreeze in the radiator looks ok. So my question is could it be the intake manifold gasket that is leaking?