Converting a Car to Run on Vegetable Oil

I haven’t owned a car since college — and back then it was my father’s hand-me-down boat of a Buick LeSabre. This time around, I wanted my daily drive to have less of an environmental impact. Because there’s no viable plug-in hybrid on the market, I had to look elsewhere.

I read a few articles extolling the virtues of converting old diesel cars to run on used cooking oil. Unlike biodiesel — which is processed so it can be poured directly into the car’s diesel tank — waste vegetable oil (WVO) is a quick and easy system ... supposedly. But because it requires installing a second fuel tank, it turns out the field-of-daisies utopia is a little harder won. And you, get to benefit from my steep climb up the learning curve.

Nightmare reality No. 1

You have to buy a used car. Converting a new car will void the warranty, so people commonly get an ’80s-era Mercedes or Volkswagen. I decided to go with a Mercedes 300D because they’re tanks, they run forever, and they look awesome. Unfortunately, they’re also incredibly in-demand (beware of scam artists and eBay bidders’ fervor), and they can go for thousands above the Blue Book value. Finally, after fruitlessly searching for weeks, my ex-boyfriend mentioned his fiancée had one for sale. The lessons here: Stay in touch with your exes, and never underestimate the power of whining.

Nightmare reality No. 2

You have to install the tank yourself. After buying the kit from for about $1,000, you can drop another grand on a mechanic, or you can DIY for free. But doing the work yourself presents a problem: The Greasecar instructions assume a lot — for instance, that you have intimate knowledge of the technical workings of a Reagan-era vehicle. I solved this issue by taking a community college class and offering up the installation as a group project. Even with all that combined technical skill, we still relied on forums such as and the Greasecar site.

Nightmare reality No. 3

You have to deal with the aftermath of the installation. These cars are old, and stuff fails, especially when you tax the system by adding a second fuel tank. I spent another grand having a mechanic replace a burnt out fuel pump and worn engine mounts, among other glorious technical breakdowns. My investment was suddenly equivalent to a year’s worth of diesel. Good thing I wasn’t into WVO for the cost savings.

Nightmare reality No. 4

You might be breaking the law.Technically, WVO isn’t an EPA-approved fuel, nor is it taxed. And you know that the gov’ment likes to tax anything it can. But WVO use has become so common in California that many people are ponying up their 25 cents per gallon in state fuel taxes. On top of that, you have to get the oil from restaurants, which usually pay disposal companies to get rid of it. Make sure you get the oil directly from the restaurant and not out of the disposal company’s holding tank — dip your hands in the latter’s vat of grease and you’re stealing.

Nightmare reality No. 5

You have to filter old, gross oil. I have a friend who stopped eating at his WVO-supplier pizza place because their oil was so nasty. Find an establishment that uses high-quality oil and changes it frequently, or you’ll never eat out again.

So after all this, was the time, expense and gigantic learning curve worth it? Actually, yeah. But it’s not for everyone, and it’s only part of the solution to our environmental problems. As soon as that plug-in becomes available, my name is first on the list.

Story by Annemarie Conte. This article originally appeared in Plenty in March 2008.

Copyright Environ Press 2008