Why not use just straight vegetable oil, if biodiesel is made from the same stuff?
While diesel engines can burn straight vegetable oil (or SVO as it is commonly called), there are many limitations that prevent it from being used as a fuel replacement. SVO is much thicker than refined fuel, and can only be used as diesel fuel when it is pre-heated prior to being fed to the engine. Simple systems exist that use heat from the cooling system to heat the incoming fuel prior to injection into the engine. But in this case, the engine must be started up and shut down on regular diesel fuel or biodiesel, then switched to SVO while the engine is running. For this reason, SVO isn’t as user-friendly as biodiesel, and isn’t recommended for most people. In addition, the lack of a fuel quality standard and the wide variety of contaminants commonly found in SVO make for inconsistent user experiences.
