Actually as far as Mazatlan most fuel is ULSD. Try to use Arco where possible, all of theirs is. We asked the pemex just past the san miguel toll booth just north of los mochis and he said his is ULSD.
Have been to Mexico twice, ~ 600 gallons fuel with no ill effects.
2017 Haulmark 45' Super C 600hp, 12 speed I shift transmission, tandem drive axles, 3 stage engine brake, towing 26' trailer with an 08 explorer inside. Jim
Recommend you take two OEM fuel filters and one oil filter, make sure you drain your water separator each day preferably in the morning before you start driving. Diesel fuel in Mexico is known to have a high water content so be aware also lotta sulfur it may stink
It is my understanding most diesel in Mexico is LSD rather than ULSD. No idea of consequences of using it in newer diesels. But I know it has been discussed before here or other RV sites.