Motorway is never a good place to have an issue with a car.
I was lucky last year and my 12v thermostat stuck in the open position.
I also had to search the world and eventually found a new one for $70 in a spares shop in New Jersey.
Bless the internet,how hard would it be building/maintaining our cars with out it.

Remember the days of phoning a spares company and asking them to send a catalog...then posting a cheque and waiting for you part to arrive