i have an 04 suburb with 80,000 miles that has oil going somewhere. last time oil was changed it was not even showing on dip stick..yesterday it said check engine oil, and sure enough it did not show on stick again so i took it to have oil changed and they said it only had two quarts in it. also was a gallon low on antifreeze. but nothing is on my garage floor, where it is parked every nite..i called my mechanic and he said it might be the pcv causing the oil, but not sure about the antifreeze.. any help would be greatly appreciated , thx. dennis