I own a L12B Honda Fit/Jazz. I have never felt roughness at idle during my 6 months of ownership. I had oil change yesterday where they drained and filled Honda Recommended Synthetic Oil.
My ideal expectation was that engine should've been more smooth. But to my surprise, I felt roughness at idle. Whole car body vibrates at idle and it seems very unlikely. Usually, I will not be able to hear the engine at idle, when sitting in car with all windows rolled up, but now I can hear it clearly and vibrates a bit more during cranks.
What would be the problem? Did the Service center guys mess up anything?