Oil is going to be for a 2003 Nissan Pathfinder with the 3.5 v6 has 130000 miles. Most of its life Pennzoil conventional fram tough guard. For about the last 30000 had Castrol GTX high mileage 5-30. Last oil change had a jug of edge black bottle 5-30. This forum for High Mileage like Valvoline MaxLife. I want to move to a full syntheatic. What full synthetic High Mileage oil should I run?