I recently started taking my Z into the GM dealer to have the oil changed and noticed my level on the dip stick has been over the operating range. Whats going on GM I'm sure they didn't overfill it ! when I change it 5qts its right in the operating range. And also the filter they use looks the same size. Any thoughts or suggestions ? And before anyone says change it your self, I figure its only a few extra bucks and I don't have to get dirty..

 

Are you sure about the filter? The original AC PF25 filter has been replaced by a smaller one. That might make a little difference. Also, the owner's manual specs 4.5 to 5 qts. in different years (I have no idea why ). I have always used 5 qts.