I have this information from a petroleum industry executive. The Pemex diesel is LSD. In January it is supposed to be ULSD. I was also told that Arco now has some stations in Sonora that have ULSD. 2 ...
The most helpful additives prevent bucking and stalling. Foreign gas stations are offering litros completos. Try adding 8% onto the price of Pemex gasoline and diesel then that's the price you pay at a crooked station.