You have a friend that believes hitler is 126 years old and still kicking in Argentina?

It's not so much how long it would take, but whether the submarine would have had enough fuel to get there. Herwig and Bercuson wrote Long Night of the Tankers, which is on the 1942-3 U-Boat campaign against tankers in the Caribbean. Using Type VIIC boats at first, the boats were able to make it there, carry out some strikes, and return home on fumes. This was accomplished by such measures as running on one engine only. In theory, then, a one-way journey to Argentina should be possible, especially with the larger later-war Type IX boats, and even more so with the assistance of the Type XIV "milchkoh" (milk cow) mid-ocean supply uboats.