BioDiesel
Since I bought my car, I've been interested in running it on BioDiesel. This is an organic fuel processed from vegetable oils. It runs much cleaner than mineral diesel and can be made from new crops such as olive, corn, soy bean, rapeseed or from Waste Vegetable Oil (WVO), that your local hamburger joint fries it's fries in.
I opted for WVO, it's the cheaper way to go, because it's FREE. I asked the manager of a local restaurant that I frequent if I could have some of his used oil that was in the fryer tanks. Without even blinking, he said sure. The kitchen manager was there, she looked a little quizzical but told me to drop off a bucket for them to fill.
I used a variation of Mike Pelly's recipe to make my first batch. Instead of tritrating to find out how much lye and methanol (Warning: these are caustic chemicals, use protective gloves, clothing, eye protection and do not inhale vapors) to use, I made 1 liter mini batches as outlined by Joshua Tickell, in "From the Fryer to the Fuel Tank".
This is what it looks like after it's been brewed and filtered.