Just changed the oil in my Civic 1.5T with 39k miles. Used Quaker State Synthetic 5W-30. The engine sounds a smig quieter, and feels smoother. This may just be because the oil is fresh, though. The old oil as changed mid June, so 7 months, and it reeked of gasoline. Almost all short trips, so the worst case for dilution. I've mostly used 0W-20, since all trips are short, and the engine seems happy when cold with the thin oil. No more, though. Gotta find someone to give my extra 0W-20 jugs to now.