My Accord has a ping here or there occasionally when going up hills, moderate acceleration etc. I use our local Shell station and its stays very busy, so it always has "fresh" fuel. About a month ago it was pinging almost any time you would accelerate rapidly or go up a hill, but I am thinking that was just a bad tank of fuel. Now its just a couple pings even now and again. My question is, would there be any harm in using a higher grade of fuel than recommended? This should stop the occasional pinging, but I have read that higher octane than necessary can leave more deposits behind and will not burn as clean as it should due to being more resistant to ignition. Can anyone confirm this?