I have acess to a good supply of vegetable oil, and have been looking into making my own bio diesel. I would like to find a little more information regarding this, so I can see if it is economical to do. The nearest place I can purchase bio diesel is about a two hour drive away. My current questions regard the removal of the sodium hydroxide from the oil after treatment, because it seems like that would eat aluminum pistons and heads like they're good. And what exactly is its purpose and the purpose of the of the methanol added to the mixture.

 

If you are good with chemistry you can look at this PDF www.nrel.gov/docs/fy04osti/36244.pdf

Looking at the first 30 pages or so will tell you why to use methanol and a catalyst while showing you chemical formulas. This is one of the more technical documents I have found regarding biodiesel chemistry I am assuming you have already looked at plenty of places just telling you a to mix "this and that" then biodiesel it's all transesterification.