With crude  imports  via  Louisiana down 5% year on year, according to US customs data, and 

a  tight  Colombian  Vasconia  market, differentials  for Gulf Coast sour benchmark Mars have 

steadily rallied since late November, according to S&P Global Platts data. 

Platts assessed prompt Mars at WTI minus $1.55/b on Monday, its strongest level since Febru

ary 2016.