By Eric Peters

A moped -- or hoofing it -- are not the only answers to the energy crunch. If you own a diesel-powered car, truck or SUV, salvation may be as close as your local greasy spoon.

It's possible to run a diesel engine on used -- albeit filtered and otherwise prepared for internal combustion -- fry oil, also known as Waste Vegetable Oil (W.Va.). There's also Straight Vegetable Oil (aka "SO" and a bit less stinky), a mix of grease and diesel -- or "biodiesel," which is also sourced from vegetable oil or animal fat.

The upside to "going greasy" is liberation from the tyranny of OPEC and $3 per gallon fuel; theoretically, you may never have to visit a gas station again.

The downside -- well, downsides -- are that fry vat fuels only work in compression-ignition (i.e., diesel) engines -- and that there's "some assembly required." You can't just pour "Mickey D High-test" into your tank and motor on.

But it can be done -- and it does, indeed, work.

The fact is that the inventor of the diesel engine -- Rudolf Diesel -- intended his design to run on vegetable oils. But vegetable-based fuels were supplanted by petroleum-based diesel fuel, principally because it was (at the time) a more effective fuel. And of course, at the dawn of the automobile age some 100 years ago, fossil fuels were both incredibly cheap and incredibly abundant. The United States produced more than enough to provide for its own needs; there was no OPEC -- and no worry about Middle Eastern oil barons, terrorism or dwindling supplies.

Today these are very real problems -- which explains the resurgent interest in feeding diesels something other than refined dead dinosaur juice.

Vegetable oils -- both "straight" (WVO/SVO), mixed (WVO/SVO/petro-diesel) and "processed" (biodiesel) -- can work as fuel in a diesel engine because a diesel relies on heat and compression -- not spark -- to ignite the air/fuel mix that creates the power that moves the car. This is why diesel engines are also called compression-ignition engines. It's also part of the reason why diesels tend to be much more durable and long-lived than gasoline (spark-ignition) engines. The fuel in a diesel provides lubrication as well as power. Gasoline, in contrast, is a highly volatile solvent -- and can (and often does) wash away the thin film of oil that keeps internal engine parts from grinding themselves into an early grave.

But don't call Col. Sanders just yet.

In order to run either WVO or SO in your diesel vehicle, you'll need to prepare the fuel; and you'll need to prepare your vehicle by modifying it to accept the different fuel. For WO and SVO, you'll typically need a separate tank, plumbing to heat the tank using engine warmth (to keep the vegetable oil from congealing, at which point it won't get you anywhere), a new filter system and related bits and pieces.

WVO and SVO systems are designed to work with most (but not all) diesel engines and cost approximately $700. (For more info, see and click on "products").

If you work the math, the conversion should pay for itself after about a year of driving -- and will cut the emissions output of your vehicle by 50-75 percent right away, without affecting power or performance.

But you still have to get the grease.

If it's SVO -- rapeseed, canola, peanut oil, etc. -- you can buy it from any store or supplier that sells it in bulk. But it still needs to be degassed and deacidified -- and absolutely free of water (which diesel engines do not like one bit). WVO can be had for your favorite price -- free -- by negotiating a deal with an understanding local restaurant owner. But once you get the goo, it's got to be prepared for use as a fuel by filtering it (to remove water and impurities, including any stray french fries and leftover nuggets of General TSA's chicken) and/or adding viscosity-enhancing agents to keep it from congealing.

Biodiesel also must be procured by purchasing it -- if you can find a supplier -- or cooked up at home via a chemical process called "transesterification" in which glycerin is separated out from the fat or vegetable oil. It's kind of yucky -- and definitely labor intensive. Plus, you still need to have a small tank/supply of dino-juice diesel for cold starts -- and to help purge the fuel lines to keep them from getting gummed up.

And there's the rub.

As bad as it is to pay $3 per gallon at your local fillin' station, the only work that's required of you is opening up your wallet. No filching buckets of loathsome excreta from the dumpsite of local fast food joints -- then lugging them home for filtering/mixing/treating. And, of course, both conventional diesel (and gasoline) are available everywhere -- so no worries about finding your next fill-up, even on a dark and stormy night.

There's also the smell to consider.

While no one likes the New Jersey Turnpike ambiance of an idling diesel engine, switching over to grease for fuel will saturate you in cholesterol cologne -- the heady, high-class ambiance of the fry station at Wendy's.

It's not for everybody -- and won't help if you're trying to diet.

There are also warranty issues to consider -- if you want to avoid losing yours, anyhow.

Proponents of vegetable oil/biodiesel claim that there should not be any negative effect on a diesel engine's function or reliability as a result of installing and properly using a conversion system -- or the WVO/SVO/biodiesel fuel itself. But warranties are often very persnickety and heavily lawyered-up with clauses and "buts" and "whereases" about just what an owner may -- and may not -- do with his vehicle in order to maintain coverage. Any "modification" or use of other-than-recommended fuel could result in the manufacturer balking at reimbursement -- even if the problem arguably had nothing to do with the use of WVO/SVO or bodiless.

The hassling of proving it didn't, forcing the manufacturer to pay for the cost of fixing whatever broke could be the price you pay for going "off the grid," fuel-wise.

On the other hand, if you own an older, long out-of-warranty diesel, this could be just the ticket.

And the next best thing to a free (if a little aromatic) ride.

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