So I converted my 1981 Mecedes Diesel to run on waste vegetable oil Last summer. I wanted to do it years ago but I didn’t, largely due to the advice given by the JourneytoTomorrow.org web site. The site looks very informative and thoughtful, however I am now of the opinion that it’s “facts” are presented in a highly biased and opinionated manor, that ended up bullying me into not doing a dual tank SVO (Straight Vegetable Oil) system by presenting it as some sort of very bad idea. It’s not a bad idea, it might just be a good idea. In their web site they refute other’s claims that it’s not a bad idea. I’m going to take time to refute some of their assertion. Journey to tomorrow’s authors makes bio-diesel, and they feel they have to criticize any competing ideas.
Also I believe that running some striaight diesel, or better yet Kerosene in one tank is preferable. Even though you don't use much of it, it's a solvent, and it helps to stop build-ups in your filters, lines, and inside the motor too.
They present the idea that making a Mercedes diesel run on SVO is “a terrible thing to do to a great engine.” This is based on a fallacy that these cars are somehow indestructible. Well, firstly, screw you I’ll do whatever I want to do with my property and it’s not your right to judge it. If you can get a couple of years of lower pollution, low cost fuel use out of one of these cars then you’re ahead of the game. The biggest mistake is getting an old car and somehow worshiping it. If you’re gonna use a car daily it won’t be a show car, and don’t expect that if you baby it will work forever. Old cars are a good way to waste a lot of money. Never pay a lot for an old car, get your use out of it, and know when to cut loose and get another one. The fact that these cars last so long was an unintended consequence of making them so well. Mercedes has reportedly fixed this “problem” and they cars are not being make differently. They were not designed to last 20 years, they rust and wear out. An old car can be dangerous as well as expensive, don’t get attached, it’s not a person, it’s a car.
Yes, the engine last a very long time, but the automatic transmissions die regularly, the cars rust and wear out just like any other car, these cars are not meant to last forever. A 20 year old Mercedes was a thing of beauty, but now most are inefficient, oil burning, rusty, cars that if you get a decent one, should give you a few more years of service. The argument that they present that using SVO in this car can take 20,000-50,000 miles off the engine life falls short mostly because the engines don’t up and die, but rust, electrical problem, transmission and suspension parts failure will stop these cars years before the engine dies . I have owned 4 old Mercedes in the usual so-so condition that you find most 20+ year old cars, and they all did from transmission problems. These cars are so heavy that the real shame is to run them on petroleum diesel, getting almost 50% of the mileage of a smaller lighter more efficient VW diesel.
They only recommend “a professional” (read as “expensive”) one tank system as the only way to burn SVO. I believe this is a bad idea. The beauty of a two tank system is it’s easily un-doable, and easy to switch to regular diesel if you experience any problems on the road. If you use waste SVO it can be un-relyable, and having a back up fuel system is a great idea. The lower cost of a dual tank system makes it more affordable for more people to try it out, and once again “investing” good money in an old car is never a good investment, so a dual tank system is ideal for an older car. Everything in the system can be easily removed, and put into the next used car.
So they had me convinced that making bio diesel was the only way to go, but now I’m not so sure. Making bio diesel is an involved process, especially for something you intend to burn. Making bio diesel requires a dangerous chemical, methanol (aka rocket fuel). Absorption of methanol through human skin can cause blindness and possibly even death. In making bio diesel, you produce Glycerin. Glycerin, a key component in explosives, is also dangerous and highly flammable. Accidents do happen, and I believe if you can avoid dealing with these dangerous chemicals you should, even if you agree with some that it’s not the best way to get every last mile out of a 25 year old engine.
The 1981 has been going for more then a year a year and saved me over $1000, and is saving it's current owner much more, he commutes. This summer I converted a 1984 300D and it’s running fine. All in all I've burnt hundreds of gallons of waste vegetable oil successfully, and I recommend it to anyone interested.