I've been running diesel from truck stops for over 4 years now. I just bought fuel today, 97 gallons at $3.99 a gallon. I have to say that I have not bought "hot" fuel at any time. The tanks are underground at Flying J's. The fuel I purchased today was far far colder than the ambient temperature of about 80 degrees. I have yet to buy fuel that is as warm as the outside temperature in the summertime.