Unlike schoolchildren, ranch trucks don't get a day off for inclement weather. They have to be ready to go for upwards of 12 hours, even in conditions that would strain other vehicles. And depending on the ranch's location, trucks may have to endure both chilly morning temperatures and astronomically high temperatures by the afternoon. Both extremes compromise a truck's performance. Cold weather strains the vehicle's battery and affects the consistency of motor oil, making the truck difficult to start. Overheating, though, represents a greater challenge to engine components. High temperatures can cause the water within the engine to evaporate, while humidity can cause it to swell, blocking much-needed oxygen from the engine. Any of these conditions could leave a rancher stranded far from the homestead.