I'm curious that your destination for the butter seemed so nonchalant about it. Aren't we talking 12 hours on the road from El Paso to Mexico City? Or less than that?
I know there are insulation blankets/packs which can delay the melt. Did you use anything like that? We used to use them when importing chocolate from the United States and Europe to Japan. But these were container vessels mostly in the late summer and fall, nothing comparable to truck temperatures in Mexico in July.
No, it was loaded straight onto an empty dry van.
No cooling blankets, paks or anything.
I was still on the dock when the Mexican driver pulled away. He just shut his doors and left.
As to the time from El Paso to Mexico City, I don’t know what the road conditions are, but I expect it’s lengthy.
The trailer was one that wouldn’t be allowed on US roads. No ICC bumper, most of the lights knocked off, and looked like it should have collapsed at least a year earlier.
The tractor looked like A 1970’s model.
All in all, not confidence inspiring.
A friend of mine has been to Mexico many times, his advice was don’t ingest anything not imported.