section_path: Chemical analysis/Chemical properties
section_name: Chemical properties
paragraph_text: Chemical properties
  
  Most diesel fuels freeze at common winter temperatures, while the temperatures greatly vary. Petrodiesel typically freezes around temperatures of −8.1 °C (17.4 °F), whereas biodiesel freezes between temperatures of 2 to 15 °C (36 to 59 °F). The viscosity of diesel noticeably increases as the temperature decreases, changing it into a gel at temperatures of −19 to −15 °C (−2 to 5 °F), that cannot flow in fuel systems. Conventional diesel fuels vaporise at temperatures between 149 °C and 371 °C.
  
  Conventional diesel flash points vary between 52 and 96 °C, which makes it safer than petrol and unsuitable for spark-ignition engines. Unlike petrol, the flash point of a diesel fuel has no relation to its performance in an engine nor to its auto ignition qualities.