Much west coast USA independent brands are refined by VALERO. Ever try to find an Atlantic Richfield refinery? Good luck. Much of Mexico's Premium is made in the Shell/Pemex joint venture refinery in Deer Park, Texas. Mexico forbids the addition of alcohol but still lavishes use of MTBE in many areas.
The name missing here is
TOP TIER GASOLINE
And administered by the American Petroleum Institute
Personally I give small credence to the API. There is ZERO checking and there is ZERO monitoring. As long as the refiner belongs to institute and submits numbers they can gain Top Tier status. "Your Rights As A Robbery Victim" as read to you by a member of the American Association of Holdup Artists.
Pemex does insist that UBA Premium really is ultra low sulfur. And being Mexico, a guarantee that different loads of fuel wont get "cross contaminated" is a joke. Some independent barges hauling fuel from Topolobampo, SIN. to Pichilingue BCS, dump a load of gasoline into a barge that just crossed with diesel.
And forget tetraethyl lead spiking. Lead is now extremely expensive and limited to some aircraft gasoline. TEL has never been manufactured in Mexico. Diesel marina and aircraft gasoline is impossible to get ahold of. Ship's or Aircraft manifest is needed and 110 low lead is almost seven dollars a gallon.