My thoughts are along the same lines as mountainbike’s and db4690’s thoughts.
When somebody tells us only that maintenance has been “regular”, “nothing special”, and only mentions oil changes–rather than giving us specifics regarding odometer mileage and elapsed time intervals–it causes me to believe that the vehicle has gotten only the bare minimum of maintenance. And, as most of us are aware, the bare minimum is not sufficient in many instances.
Perhaps I am wrong, and if the OP can provide complete answers to all of the questions that have been asked, then I will no problem being proven wrong.
I am currently taking it to Honda Dealership here in San Antonio. I change my oil every 5,000 miles or when the car indicates it needs a A or B service. Sometimes, I go before it gets to that point. I had my transmission fluids drain and replaced in March 2013. Also, I had to take my car in for a safety recall in 2011. The first one is software update to prevent transmission damage. The second was update fuel injector timing and VTC timing at cold start that may create deposit on oil control rings that could contribute to increased old consumption.
This same thing is happening with my 2010 honda accord coupe. Im getting the rattling when i get to 50% oil life and have to change oil at that point now. This is a frustrating problem because every mechanic ive explained this to has no solution except keep changing the oil.