Thanks for the tips. Not looking to harm them. Neighbor already did one in starting the car.I imagine pepper spray lightly on the underbody could help around the cold spots.
I would make sure not to spray any hot spots like the exhaust. Avoid air and ac intake. Theb for caution i would top down wash(no undercarrige) and drive it with ac off for at least a full heat up/cooldown cycle.
Warn your mechanic. Wear gloves while servicing.
Or find a less awful smell cats cant stand.
Napthala - moth balls, are poison. Pepper spray will just make you wish you were dead.
Ammonia may get a desired easily washed off result. Really think of respiratory irritants but not outright poison.