I have a 2000 Dodge Intrepid R/T, 3.5 w/auto stick. I run Valvoline full synthetic 10w-30. It will usually use about 1/2 qt. between oil changes (5000 mi) but it seems to be using a little more than usual now. It has 106,000 on it. I was thinking about going with a high mileage oil or is that stuff just a gimmick? Maybe go back to conventional? What do you guys think?