But thanks to today's cold starting technologies they are very effective. Modern diesel engines can start even in cold weather with minimal effort, just like their counterparts. Below about 40°F, some hydrocarbons in diesel become gelatinous. Since an engine depends on fuel aerosol, you don't want sticky fuel. This is when the glow plugs go into the clutch, which are heated by the battery and help heat the fuel so it can vaporize properly. Running in cold temperatures is not a big problem for gas engines because gasoline is much more flammable than diesel. Even at room temperature and pressure, gasoline is part vapor, so the vapor would ignite before the liquid