I'm not a diesel user but I am an rver and an avid news follower. Here is an article from November 29th, 2019.
PEMEX Looks to Suspend The New Norm For Clean Diesel.However, at the beginning of the year, a district court granted Pemex protection and suspended the forced entry of the new provision in most of Mexico. The suspension limited the mandatory distribution and sale of DUBA (ULSD) to 9 percent of the country, including Mexico City, Guadalajara, and Monterrey, as well as the northern border. A final court decision on the most widespread supply of DUBA has not yet been made, but court documents, reviewed by Reuters, show for the first time that Pemex is fighting in Mexican courts to suspend the rule indefinitely. Continuing to use high sulfur diesel could save Mexico money by limiting imports and extending the deadline for truck manufacturers to install DUBA compatible engines. However, it could add to the perception of a recession of the government of President Andrés Manuel López Obrador in the fulfillment of environmental commitments.