Hi all, my Prius makes one slight clunk noise when the engine engages during normal driving. This is when the engine is off (driving with battery or regening) then the engine comes on to supply drive power. Once the engine is on, it drives great. i don’t know how the engine marries to an already running drive train. But my sense is that mechanism re engaging is what is making that one clunk. I am at 100k miles and am going to replace the tranny oil with oem oil soon. I am guessing this is the first time it’s been done. I’ve owned the car since 60k. Is there anything I should look at while I have the plastic ‘skid’ plate off the bottom?