I am not sure of this but it seems to me the engine has been more buzzy/louder since my first service at 10,000 miles. I have no measurements of sound just a general subtle sense that the engine sound seems somehow more noticeable than before. I have checked the oil level and all seems well. Is it possible that anything can be done during the oil & filter change/tire rotation/fluids check that would increase the engine sound? It is not enough for me say anything to the dealer and not expect that “are you crazy?” look.
Check to see if any software campaigns were installed during your oil change. If so, that may have caused your engine management systems to alter a bit. At least that's what I feel happened to me after the software campaigns were done on my vehicle, but after putting more miles on, everything quieted down.
I have never looked but I think there is an aero panel that has to be removed to change the oil. Hard to believe they would leave it off but anything is possible and it would probably make the car sound different.
Yes, there is a large aluminum panel covering the oil change area. As @Chuck says, it is hard to imagine that the mechanic didn't re-install it, but here's what it looks like (circled): I can't think why changing the oil would have an impact on engine noise. Perhaps if something wasn't quite right when the tires were rotated (lost a balance weight or similar), but that would be noticeable in EV mode. I assume from your description that it is the engine that sounds different...
Not likely the issue, but after service bulletins are installed, the car reverts back to Econ off. I always keep Econ on and it took me a drive or two to notice what had changed and to turn it back on... and yes, I know there are those who like it off all the time anyway.
When we bought our Prius, it came with 2 years of Toyota Care, which included oil changes, so I had them done at a nearby dealer. When I performed my first oil change on the car, I discovered that the filter chamber had no element in it. Hard to imagine, but not outside the realm.
Having changed my own oil, I can imagine the cover may not be properly installed, and vibrating with the engine. There are retaining tabs in the middle of each side. For my first oil change, I did not engage those properly, and the thing was loose.
Wow. I wasn’t expecting such good information in a short amount of time. I will check on these and report back. The picture helps.
I've noticed the engine seems louder in winter. Could be my perception, but this the second winter it's happened. No idea on the logic. Could be anything from cold weather engine controls to sound deadening being less effective when cold. I hear the same thing as others, a little louder, buzzy, moaning resonance from the engine.
I had my car since January when the temperature was far colder. Somehow the clarity engine noise seems more noticeable since the oil change. It is not low on oil, when the engine is cold the oil is between the 2 marks. If the lower mark is the cold oil level then maybe it is a little overfilled. The problem is I do not run the engine often enough to be sure and the different is not big enough to make me make a big deal about it without sounding like a wacko. My hope is since nobody is experiencing anything abnormal along these lines then my Clarity is probably ok too and it is just a perception error on my part.