Veg-Oil Biofuel Options

The following is an excerpt from an email I wrote regarding biodiesel and WVO options. It seems relatively coherent and on topic, so I'll include it here too. This particular discussion focuses on the Mercedes W123 family of cars from the late-70's to mid-80's.

I would characterize the vegoil biofuel options on a diesel (especially on these W123
Mercedes) as a spectrum. Here are a few waypoints:

1. Commercial biodiesel. Meets ASTM standards, should run through the
vehicle without any noticeable effect on performance, economy, or
maintenance requirements with the exception that you're likely to go
through two fuel filter changes (actually four, since the car has two
filters that will probably need to be changed twice) within the first five
or ten tankfuls. On some older cars it may be necessary to replace a few
rubber fuel lines after a year or two of use, and on the W123 MBs the
gasket around the fuel filler neck will probably look "melted" by
overspill. Around here, getting up to B20 at filling stations is becoming
feasible, but if you find a local or regional distributor it is possible
to have this fuel delivered to your home. This is what I generally do - I
receive 55 gallon drums at a cost of about $3 a gallon plus $20 delivery
and have a hand-cranked rotary pump for filling the tank.

2. Homebrew biodiesel. For a conscientious tinkerer with adequate time
available, a high quality homebrew can be achieved using good quality
restaurant oil (upscale Chinese and Indian places have the best). Your
investment starts with building a reactor (the Appleseed Processor
designed by Girl Mark - Mario Alovert - can be built for around $100) or
buying one (about $3000, give or take $1500). Then you purchase methanol
and lye (which is getting scarce due to meth lab fears) at a cost of about
$0.80 - $0.90 per finished gallon of fuel. Making a batch takes about 2
weeks including drying time, but only a handful of hours in the processor
and washer, and probably only an hour of direct involvement of the
operator.

3. Straight Vegetable Oil. With high quality WVO or purchased SVO, a good
conversion kit, and proper operation, this option is probably as safe as
the homebrew option, and may be a little less time consuming. Instead of
acquiring the processor, you'll have comparable (but probably higher)
costs involved in converting the car, and comparable (but lower) time
commitments in filtering and drying the oil.

4. Waste Vegetable Oil. The only difference between this option and the
previous is the quality of the oil, and realistically you can only tell
that by titration. When oil is overheated, or heated for too long, the
triglycerides break down into di- and mono-glycerides plus free fatty
acids or FFAs. The FFAs are the problem really, and if possible you want
to remove them from the oil before you burn it in your car. The process
for doing this is de-esterification - really, a partial biodiesel
(transesterification) process. Without this process you may be looking at
taking significant life off the engine - or you may not. The research is
still quite unclear whether running VO at all is bad for modern engines,
let alone running bad VO.