I've been running M1 up to about 9,000 miles before changing the oil in my 2003 Crown Vic and was thinking I could do up to 6,500 with the Motorcraft semi without any issues. I used to drive the Crown Vic more aggressively but now it just sees Mon-Fri 90% freeway work commutes which aren't overly hard miles, so I figured I could stretch another 1,500 miles out of semi-dino oil. Just trying to save a couple bucks when I do the oil changes, money's kinda tight. Any thoughts? Figured if I do try it I would do a UOA afterwards to see if it's okay or am I taking a gamble.