- Mar 29, 2017
Hi, everyone. I recently purchased a 2007 Mercury Grand Marquis with the 4.6L V8 Triton/Modular engine. The car, as it sits right now, has 61,000 miles on it. To my knowledge, the car has only had dino oil ran in it all of these years. I've heard about switching to full synthetic on an older car can cause leaks around older gaskets. The car is completely dry underneath it, right now. No oil pan/valve cover seepage or signs of rear main leaking. Can I switch over to full synthetic on this car without worrying? I've been thinking about running a synthetic blend oil to try to slowly "break it in" for synthetic, so to speak. I don't know if that would make any difference. What do you guys think? TIA!