I wanted to verify the dealer was replacing the oil filter. I assumed they would remove the plastic splash guard between the bumper and stock metal splash guard that's held in place by 5 wide flange fender style bolts. So, I used my wife's nail polish to paint a glob on the edge of the two forward outer bolt flanges to indicate if those bolts were broken loose.

The globs were not broken, so I showed it to the shop manager. He said, they only remove four metal guard bolts and let the metal guard hang by the forward hooks while changing the oil filter. At home, I removed the metal splash guard and found it had been wiped down to remove a streak of oil that flowed down and back from the oil filter location.

That's when I started doing my own oil changes because I think allowing the metal guard to hang and flex the plastic splash guard will eventually crack the plastic.

I had to chase the four metal guard bolt threads with a tap and die, and fortunately, all of them appear to be OK.