Unfortunately, the vast majority of pre-2002 research was based on a (now realized) flawed assumption of using vegetable oil as a fuel at ambient tempetures. The problem with working at those tempetures is that VO tends to have a viscosity 30-60 times higher than diesel fuel at 40-70 degrees F leading to incomplete atomization/vaporization at the injector heads. The result is incomplete burns, "coking" and carbonization in the cylinder and on rings, and significantly higher emissions. So, the results from teh 1980-90's test are generally negative due to engine damage.

Current VO'ers use engine coolant based in-tank heat exchangers, hose-in-hose fuel lines, coolant or electric heated fuel filters, and electric heaters for the fuel injector lines. As a result the VO is ~120-180 degrees before entering the injector making it's viscosity similar to regular diesel. This has cured the carbon deposit and atomization problems, increased efficiency, and significantly reduced emissions.

Sadly, there are a lot of unsubstantiated claims of 40-70% reductions in particualte emissions being thrown around by VO proponents, but i have had a hard time finding the actual studies these claims are based on. It seems a lot is based on an EPA biodiesel study which I am not sure are directly comparable due to the existence of methyl esthers. Unfortunately, most recent research has been on biodiesel due it's far greater market potential and organized lobby/industry.

One thing it is fairly safe to state as fact is that Sulfur emissions are reduced 100% because sulfur does not exist in vegetables oils like petroleum-based products.

Here is one study on straight VO as fuel:
Advanced Combustion Research for Energy from Vegetable Oils (ACREVO)
Contract No: FAIR1-CT95-0191
Date Prepared: July 2001

The overall combustion performance of the rapeseed oil are very satisfactory in comparison with the diesel fuel while the rapeseed oil produces almost 40 % less soot than diesel fuel...Further it can be stressed, that the shown emission results of unburned hydrocarbons (HC), carbon monoxide (CO), nitric oxides (NOx) and particulate matter (PM) confirm the advantages of RME in comparison to Diesel fuel...Concerning polycyclic aromatic hydrocarbons (PAH) there is significantly better emission behaviour of RME in comparison to Diesel fuel. There are even greater emission advantages for other fatty acid methyl esters and with oxidising catalyst no disadvantages for TESSOL. In general there is a very low PAH-level of vegetable fuels because of chemical structure (there is no PAH in vegetable fuel in contrast to Diesel fuel).

The SVO/WVO conversion company Greasecar sites this data from some unlisted study.

Here is the largest collection of studies/papers that I know of.

Great question, Jim. I originally considered TE option and was shocked to see how cheaply they were selling for.

First of all, the vast majority of MB WVO greasers are buying cheap cars in the $900 to sub-$4,000 range. Only a tiny, tiny, fraction are touching the $6,000+ offerings.

Also, it is a safe assumption that anyone paying the current highest prices, 150-250% more($9k-15k) than the historical market value, for the cars is probably not too concerned with the economics of the purchase. I think it will helpful to everyone curious about this "fad" to know the hidden costs that most VO's don't talk about. I am only speaking of those who follow the letter of the law.

Let's use my situation as an example:

I drive approx. 12,000 a year for work and another 5,000+ on camping/snowboarding trips. On the trips, my girlfriend and I have historically taken her 1991 Ford Bronco (V8). She now has a Ford Freestyle which gets ~24 mpg highway, but the Bronco is what got me looking into alternatives.

I average 17mpg city and 24 highway with my former '91 Accord. Unfortunately, Los Angeles traffic makes just about everything a city type drive during the week, so we'll call it 20mpg average or 600 gallons per year. Her Bronco averages ~16 mpg on trips or ~315 gallons per year. So, I burn approx. 915 gallons per year at ~$3.20 per gallon - ~$3,000 per year on gas.

California requires an "inedible kitchen grease" collection permit or license, these are actually issued by the Dept. of Agriculture. for ~$125 per year. The primary stipulation for the permit/license is a $1 million umbrella liability insurance policy which runs approx. $170-300 per year.

Next, the IRS requires (a debated) $0.18 or $0.24 per gallon road use tax be paid on all oil actually used(not collected) for auto fuel. So, for me that would be 480 gallons to drive the 12k per year at 25mpg and 156 gallons to go 5k miles at 32mpg highway(so, the owner of the 300TD I'm buying claims). That's 636 gallons to drive those same 17,000 miles per year requiring $114 or $152 in tax. Let's use the higher number to be safe.

For me, that is $200+152+125 devided by 636 gallons = $0.75 per gallon or $477 per year total. The current average gas price in the part of Los Angeles where I live for the last 6 months has been $3.20-$3.30 a gallon, so we are looking at ~$2.50 a gallon savings. 17,000 miles X $2.50 per gallon savings would yield ~$2,288 per year savings over my current situation.

Now, back to the gasoline 300TE. It would take 600 gallons to travel the 12,000 work miles(@20mpg) I travel and 210 gallons for the 5k vacation(@24mpg) for a total of 810 gallons per year. At $3.20 per gallon that's ~$2,600 per year.

$2,600-$477= $2,123 per year savings from the 300TD over the 300TE.

I'm buying my '87 300TDT for ~$6,500 tomorrow meaning that I will recoup the ~$2,500 price difference in approximately 15 months depending on gas prices. After that, the car would nearly pay for itself over to following 3 years. In my case, yes. I'm spending a bit more than the average Greaser to simply and semi-automate my collection and refining. Though, the system is not complete yet. I've already ramblen on long enough, but perhaps tonight I can give a brief overview to the system I am assembling.