One might think

That people who drive Semi trucks for a living would have some clue as to the care and feeding of diesel engines in general, and the characteristics of the diesel fuel that they use....

Ferinstance, that the waxes begin to crystallize out at lower temperatures, often referred to as "gelling"...and easily preventable occurrence with the addition of several commercially available additives such as Howes or Power Service and others. Generally this cost is about $20 per full load of fuel. While most diesel fuel sold north of the Mason-Dixon line is treated for cold weather, not all is, and truckers who fuel in the south and then drive north are taking their chances.....

Now, if a truck gells up, the service cost is about $150+ (labor) plus parts  to get the truck running, and the first thing they do is add one of the fuel treatments to the tank....

One might think that drivers who should know better would, when encountering temperatures below zero (Fahrenheit) would be smart enough to treat their fuel......right?I'm talking experienced drivers who have more than a decade of driving and hundreds of thousands of driving miles under them......

You'd be mistaken. While some (most?) are smart enough, many aren't.  They are surprised that their truck stopped running in the night, or that it won't start in the morning.....Like gelled diesel is a new phenomenon or something. Like the three I met today, when the mercury dropped to about -3F last night.....

(and we won't even start talking about those who have batteries that will barely start the trucks when it is 40 degrees F out......) Mechanics love these folks.....

These are people who are driving next to you on the highway guiding 80,000 lbs and upon whose judgement your safety depends....

Scary.