Followed care nut yt video to change spark plugs at 41k.Fairly easy to do but intimidating at start. I strugled with rubber hose on photo at 9 oclock and ended up not disconnecting it, it worked fine with just 12 oclock being removed. Other then that doable with special swivel tools care nut advocate for. Cylinders looked without scratches (5k oils) valves okay i guess. But i am not expert on that. One spark plug on drivers rear cylinder had more deposits then the rest along the threads and there was more carbon buildap or oil? on top of cilinder (image 2 and 3)
