Black pepper in the rad will stop a small leak. But so will putting a raw egg in the rad. But only temporary.
Go big or at least have a cold one waiting for them when they bust their junk and have to fix it or load it on the trailer.
Don't worry there's still two tires on the ground.
"Life's goal is not to reach the grave safely in a well preserved body. But to slide in sideways, totally worn out, shouting "Holy Shit, what a ride."