I have a extend cab 2008 Silverado . 5.3L no flex . 2wd. LT. The only mods I have is a driveshaft disconnect because the vehicle is used as a TOAD. A while back I took my truck to the local stealership and performed a oil burn test. Before I took it in I checked the oil and it was in fact a quart low after the 1,000 mile drive. I took it back and they informed me that the missing quart had miraculously appeared in my crankcase ! When I asked for proof low and behold there it was . I must of been a bad boy since because I recently changed the oil and after 1.300 miles my crankcase was 3 quarts low. If you have one of these oil burner GM's face it your SCREWD!!!!!!!!!!!!!!!!!