Hmmm never herd of the peppermint oil before. Have to remember that one. Rustystud's Bobcat takes the cake though.
I had a extremely lazy garage cat once. I would be working at the bench, cat in its "bed" at my feet, and we would both watch mice come to its food dish and steal a mouthful. Not to long after seeing that I had two ermine move into the garage. Hazed, poked, prodded, teased that cat so much it refused to enter the garage anymore. Told the wife she could find it a new home or I would. Since then I've off and on had the ermine, or descendants thereof, living in my garage. Curious creatures that are outstanding killers. They seem to rid me of mice and chipmunks and then move one. Come back when the critters do...
Oh and steel wool works great as long as you plug all the holes. I had a log cabin once that had no shortage of holes for critters to get through. I would "mix" spray foam with the steel wool and plug any and all holes I found. I could see where they started to chew, then gave up when they hit the steel wool. In larger had to reach spots I would take hardware cloth, cut it to the rough size of the opening, jam it in there, then secure with the spray foam.