In reply to Datsun240ZGuy :
When methanol was about $200 for a 54 gal drum my final cost was about .90 a gal. That included my meth, potasium hydroxide, and electricity. I don't know how much it is now, you need to find a supplier that doesn't try to make "all the money" on one drum. I had to go to a chemical supply place in Tampa to get a reasonable deal.
I need to dust off some old brain cells here.
The normal home brew process used 22% by volume of the methanol and Hydroxide mix. You can use Sodium or Potassium hydroxide. I liked Potassium because I could make great hand soap liquid from the glycerol that is the waste product of making fuel. Sodium is good if you want to make bar soap later. It all looks nasty but man it will clean.
So you have 100 gals of oil, you will need 22 gals of methoxide. The amount of hydroxide you need to add to your methanol is determined by a titration test. You need to get your oil to neutral Ph and some extra for the reaction to remove the mono, di, and triglycerides from the oil. What you end up with is called fatty acid methyl esters="Biodiesel". The exact titration process escapes me right now. I can find some info and post it later. It is the most difficult part of the process.
You heat the oil up to about 130F, I used to push it a little bit but you can't get over the boiling point of methanol, 142F if I recall. Add the methoxide slowly and let it circulate in the system for about an hour or so. The reaction occurs quickly at first but then slows down because the reacted stuff slows down new reactions. You shut it off and let it settle. The glycerol falls to the bottom, black nasty looking stuff, the stuff left on top is biodiesel. Drain the black stuff out and the fuel looks like tea or apple juice colored.
That is the basic method. Base/base/ prewash is just a few extra steps. Titration and all the heat is the same. You only add 75% of your methoxide at first though. Let that process for a while and let it settle out for a short time, maybe 30 minutes. Then you add the last of your methoxide and let it run for an hour or longer. Draining off some the glycerol that has reacted helps speed up the process when you add the other 25%. The reaction only needs about 15% methoxide in perfect conditions, the extra 7% is an insurance policy. After running that for another hour you add 5% water(5 gals in our case) and let it run for while.
The prewash was black belt level stuff back then. One problem you will have is water in your oil stock. Any water in your oil during the reaction process and you will make soap! The reaction is done before the prewash so what it does is starts to absorb any methanol and soaps you may have in the mix.
I usually let it sit over night after the prewash. The next day you drain all the water and glycerol off the bottom and move what is left to the wash tank or run it through your resin beads to remove the methanol and soaps.
After washing and drying, feed it to your diesel engine.
There are a lot of ways E36 M3 can go sideways with high Ph oils and bad titration methods. Too much for me to remember enough to bail any body out if they have a processor full of tan goo. You can get into playing with acids to magically break up the goo and still get fuel.