I'm getting worse fuel economy than a while ago.

 

I experienced the same results until I got the oil change at 8900miles. I averaged between 28-32 mpg, per tank, then dropped to the 25-26mpg range. After my first oil change, I jumped back to the 28-32 mpg range again. Where do you live? I live in Florida, where the heat and humidity is excessive. I plan to change my oil at 6000 mile intervals, rather than the 12k recommended by dealer.