I just did my own oil change at 5K and put in Mobil 1 synthetic oil. This is my first time using a synthetic in any of my vehicles. It may be my imagination but I think the engine idles just a little smoother and quieter. It also seems to be even more effortless when accelerating. It's only been about a week since I changed it, but I like what I'm seeing so far. According to the owners manual you must follow Honda's recommended oil change intervals, even with synthetic oil, to maintain your warranty.

Rich