I can say that I just bought a 2017 gmc Sierra 3/4 ton back in December. I stayed quite on this topic until now to get a good feel for it and see if any problems were presented. It is a z71 has 60,000 miles with 6.0 and 4.10 rear end. I am getting 15.5 MPG which is not even 1 MPG less than my...