I was recommended this thread in a Facebook expat group. I noticed you mentioned this:

"2 out of 3 custom officials (AT THE MINISTRY OF EXTERNAL AFFAIRS) said that it is OK for a foreign tourist to take an Argentine registered bike out of Argentina, as long as the foreign tourist has the "green card" for the bike."

If I were to attempt crossing into Chile with my car as a tourist by myself, and for whatever reason they said I couldn't go, what's the worst that can happen, do you know? Would they just turn me around?

Also, seeing as how this thread is quite old, I'd assume you've encountered people that have attempted to cross alone. Are they mostly successful or unsuccessful?

Thanks for the writeup and willingness to help others. It's refreshing to see.

I’m a US citizen and legal owner of a Mexican motorcycle. The bike currently sits in Ecuador. I’m looking for ways to get rid of the bike at the moment. Is Argentinian option for me?

Thank you for your excellent question. As noted, you are referring to a post I made in January of 2008, 16 years ago. At that time in Buenos Aires as tourists, Elisa and I each purchased a Honda motorcycle, she XR250 Tornado Honda and me, NX400 Falcon Honda and we were able to cross out of Argentina into Chile. In 2008, Paso de Jama was a cold and lonely mountain border pass with bored and distracted border officials and in retrospect *we illegally exited our Hondas from Argentina.
In 2008, I was quite prolific with my unwashed commentary and advice and for good reason I was sanctioned by HU. Today, I lean conservatively toward rules and regulations. The regulation is that as a tourist visiting Argentina on a 3 or 8 month tourist visa , the tourist can legally purchase and sell in Argentina a vehicle or motorcycle. The regulation prohibits tourists from exiting their legally purchased Argentine registered vehicle or motorcycle from Argentina.
Experience dictates that today the vast majority of official Argentina border posts are equipped with computers and well trained officials that know how to determine, by passport or VIN examination the status of the "tourist" and the registration information of Argentine registered vehicles and motorcycles.
Argentine registered Vehicles and motorcycles purchased by tourists will be stopped and prohibited from leaving Argentina. Argentine registered motorcycles are permitted to be in Argentina indefinitely, so I suspect the tourist might be permitted to leave Argentina, but the legally owned vehicle or motorcycle will remain in Argentina.
When Elisa and I surveyed customs officials in 2008, we did find that most custom officials lacked the training to know the regulations regarding this issue. As a tourist, I would not attempt to exit my legally purchased vehicle or motorcycle from Argentina. I am now a permanent foreign resident of Argentina and have legally exited my NX400 Honda from Argentina many times.
There exists a local Honda agency that sells new Hondas to tourists and will buy back the Honda anytime during the three year warranty period.
I hope this has not only been my mea culpa but provided useful information to tourists wishing to buy and sell a motorcycle in Argentina.
*Please, as a tourist, do not attempt to leave Argentina with your Argentine registered vehicle or motorcycle.

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Motorcycle Parking Buenos Aires, Argentina
www.xfiltrate.com
Discover how to legally Buy, Tour and Sell a motorcycle in Argentina

buy in Mexico sell in Mexico is the bottom line
No options in your case
AD: Hey there is a free Mexican plated motorcycle in Ecuador, the helmet is what I'm selling worth 2000 bucks, bike included

It would be illegal with consequences (a big mistake) to sell or attempt to sell a Mexican registered or any foreign plated motorcycle in Argentina. As a tourist from the USA you would have to enter the Mexican registered motorcycle into Argentina on a Temporary Vehicle Import Permit (TVIP) and by doing so you agree not to sell the motorcycle in Argentina.
You also agree to exit the Mexican registered motorcycle before the TVIP expires. TVIPs are issued at the border for 3 months and at some borders for 8 months. If the bike is in the country after the TVIP expires it will be confiscated by the authorities.
It is important to note that all insurance is null and void once the TVIP expires. Insurance companies are off the hook if the foreign registered motorcycle is in country with an expired, non existent or photoshopped TVIP.

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Motorcycle Parking Buenos Aires, Argentina
www.xfiltrate.com
Discover how to legally Buy, Tour and Sell a motorcycle in Argentina