I wonder if you have any links about Bulk Oil Tankers (Ships) built in the UK in the 1950's for the Argentine Government? I think they were called Eva Peron and Presidente Peron, possibly others too. Any info will be much appreciated.
There´s a site that lists historical Argentine ships, their ownership and whether they are still seaworthy or not or have been scrapped.
There are photos of the ships. if the original poster of the question knows the names of the ships or the designs, he may be able able to trace them this way. http://www.histarmar.com.ar/IndiceMercantesArgentinos.htm
In my humble opinion it is very unlikely that an oil tanker over 60 years old is still in use and for carrying oil, Nashorama, as it would almost impossible to insure... or at least extremely difficult, even under a convenience flag... but then it will be interesting to find out.