I have a 200 GMC sierra 1500 with 37,000 miles and lately I have been noticing my check engine oil level light coming on. I took it in to have the oil changed and the guy said it was 1.5 quarts low and I said WHAT?? He suggested I take it back to the dealer which is where it's going today, but has anybody else been having this problem? Why is this truck using oil like this, it's already been in the shop once to remove the carbon build-up from the pistons, please help!!!