Chile/Argentina border crossing. Paperwork for borrowed bike?
 

I'll be borrowing a bike for a few weeks. Picking up in Chile, crossing into Argentina, back to Chile.

The bike is US titled and will be legally in Chile.

Does anybody know exactly paperwork will be required to cross the border? I assume there will need to be some sort of letter of permission, but details, or even better, a sample letter would be fantastic!

best guess
 

Havea translated notorized paper stating you are legally allowed to be taking other persons bike out and back to chile . good luck, maybe best on sunday no body nos and nobody cares

It would be best to have the owner of the bike go to the border with you. If that it is not possible you can always try to do it with a written letter of permission but I have my doubts there.