I live in an area where we have a lot of Antechinus which are small native rat or mice-like marsupials.

They have been keen to sleep up on my Defender Engine and leave their droppings behind. I did some research and read that a few drops of peppermint essential oil would deter them. Sure enough they have abandoned the engine as a resting place, and I apply few drops of oil regularly.

They also liked getting up in my wife’s Honda as well, in winter time, as the engine remains warm into the night. It can be a costly fix if they chew the engine wiring. Must have been a bit liberal with the oil at one stage and when the Honda engine got warm it smelt like a peppermint factory.