Some of heavy duty trucks at the factory are modern variants from the 1990s-2000s, including the Freightliner FLD with front end in production from 1990 to 2004.
The dread bacteria at the center of this episode are not able to survive in corn syrup at any temperature. Much like preserves (e.g., strawberry) corn syrup is a hygroscopic environment, which naturally prevents bacterial growth. Regardless of the heat applied, bacteria would not be able to live or grow in this sugary liquid.
Everything Mindy explains to Lonny via radio during the sting, she could have told him in advance, which would have been a much better idea.