I'm new on here have a 2010 civic lx and was just curious on motor oil recommended for high mileage motors. Running 5w20 and only have a 111,000 miles. At what mileage should I go to thicker oil if at all? Also was thinking about doing a cold air and a downpipe. Someone told me that the down pipe might rob you on your top end and give you more low end? Any thoughts?