Alternative Diesel Fuel:
FAQ on Our Vegetable Oil Conversion
We get a lot of questions on our alternative diesel fuel setup. Instead of trying to write it all out in one article, we decided to start collecting those questions and have answered them below.
What is a vegetable oil conversion?
A waste veggie oil conversion is a process of adding engine components to a diesel engine to allow your vehicle to run on used veggie oil (the stuff they cook your french fries in). The components consist of things like extra hoses, additional fuel tanks, wiring, filtering system, potentially a new fuel pump, etc in order to use the waste oil without any type of processing or chemical additives (such as with biodiesel), and without damaging the engine.
How long have you been running on waste veggie oil?
We converted our first engine to run on veggie oil in 2009, drove it a year and put 16,000 miles on it before selling it to another family who stills runs it on "veg". We got our second vehicle within a couple months and drove it from December 2011 through May 2014 (when it was totaled in an accident). We put 85,000 miles on the Ford engine using straight vegetable oil as our alternative diesel fuel.
What kind of vehicle do you have?
Our first vegetable oil conversion was done on a 1982 Winnebago Brave, 6.2L GM diesel engine (below). Our last truck is a 2001 Ford F-350 with a 7.3L Ford Powerstroke engine (the photo at the top of this page). We used a Raptor 350 fuel pump because it handles the veggie oil better than a stock fuel pump. Our current truck is a 2004 Doge Ram with a Cummings engine, and we are making plans to have it converted soon.
What is the difference between this and using biodiesel?
Biodiesel is a chemical process to make an alternative diesel fuel out of vegetable oil. It's messy, time consuming, and potentially hazardous. Waste veggie oil requires no chemical process (and no chance of blowing up your garage while making it) and is only filtered to remove the bits of chicken or french fries. It can be added straight to a properly converted engine and runs normally if properly maintained.
Do you have to add anything to the veggie oil?
No, you don't have to add anything, but I have found that adding a common diesel additive increases the life of the filtering system dramatically. (Before I was changing and cleaning the system out every 1,000-2,000 miles. Now I get close to 10,000 miles before needing to change a filter.)
Is it better for the environment?
Yes, substantially. Waste veggie oil produces no emissions, so our vehicle only produces emissions when we run on diesel (to warmup the system and purge the system, about 5-15 minutes total) making our emissions at least 70% lower, depending on our driving habits. We minimize this even less by combining errands and other trips so that we are running on our alternative diesel fuel more often and needing to warmup and purge less often.
When do you use regular diesel fuel instead of alternative diesel fuel?
An alternative diesel fuel system like this one requires that you use regular diesel to some extent. We use diesel when we first start our engine until it gets up to normal running temps. Then as we head home for the day, or if we know we'll be parked for more than 3 hours (less if it's especially cold outside), we "purge" the system of vegetable oil by running diesel through the veg lines (our system includes a toggle switch that allows us to do this easily). We obviously use more diesel in colder weather than we do warmer weather, so combining trips is more important than ever to make the most of our warmup time on diesel fuel.
Does an alternative diesel fuel system impact fuel economy?
No, not at all. We get the exact same MPG with our vegetable oil conversion that we do running on diesel.
Does it cause more wear and tear on the engine?
For the most part, not much. If you're maintaining your system well, cleaning it as needed, and purging it properly, you aren't likely to have any issues. You may find that your stock fuel pump can't handle vegetable oil as well, so until we upgraded to a better fuel pump (described above) we had more wear and tear on it, but otherwise our engine has handled it really well.
Where do you find the vegetable oil?
Any place that uses cooking oil is where you want to ask. Simply walk up and ask them for their oil. Some are under contract to sell their oil, others have to pay to get rid of it and are eager for you to take it off their hands for free. Check out fast food restaurants, grocery stores, etc. I don't recommend paying for it.
Is it hard for you to find waste veggie oil?
We've traveled all over the country for three years running on waste veggie oil, and only once needed to run on diesel (and that was more for a lack of planning and time than it was not being able to find oil). There was one other place where we couldn't find any for free (Miami, if you're curious) and chose to purchase it since it was still cheaper than regular diesel. There were places where it was hard to find oil that wasn't so dirty it was pointless to try to run through our filtering system, but for the most part we had no problem finding it anywhere in the nation. Whether you're traveling or not, finding a good source and building a trusting relationships with them takes the most time upfront.
Is it always free? Have you ever had to pay for it?
We've only paid for our alternative diesel fuel once in three years (in Miami). Every place I had looked either had a contract for their oil or didn't have any. Paying for waste veggie oil (or biodiesel) is still cheaper than paying for regular diesel, even if it's not our first choice.
How much money do you save with your vegetable oil conversion?
At the time we're writing this, diesel is about $4 a gallon. We have 100 gallon dirty tank, meaning each time we fill up we're saving $400. We fill up our veg every 1-2 weeks depending on how much we're driving. We only fill up our diesel tank every 6-8 weeks. So instead of spending $150 a week, we're spending $150 every other month, saving at least $1,000 every 6-8 weeks.
What kind of engines can be converted?
Any diesel engine can be converted, but with newer technology it makes it more difficult. The sensors in the newer engines like to throw on "Check Engine" lights and don't like the color of the fuel. This doesn't make it impossible to convert a newer engine, just a pain. You can bypass some of sensors when you're doing the conversion, or remove the sensors altogether, however be aware that any vegetable oil conversion will void any warranty you might have, and the more electrical components in the engine might make it more difficult to repair yourself (and good luck finding a mechanic who doesn't think you're crazy or wants to blame any and all engine problems on your veg). Regular gasoline engines cannot NOT be converted. Please don't try that.
Why can only diesel engines undergo a vegetable oil conversion?
The man who invented the diesel engine, Rudolph Diesel, originally invented it so that farmers could be more self-sufficient, growing things like peanuts and making their own alternative diesel fuel. Most diesels now run on a byproduct of producing gasoline. Gasoline engines are not combustible like diesels are and won't burn waste veggie oil.
What is needed to convert a diesel engine?
For starters, you need to consider a place for an auxiliary fuel tank. This could be in the trunk of your diesel Mercedes, the bed of your truck, or where your spare tire is. You'll need at least a clean tank, but it helps to also have a dirty tank (so you can pump oil directly from one, through your filters, and into the other before going to the engine). You're also going to need various hoses and electrical lines, fittings, solenoids, optional gauges (to know when your alternative diesel fuel is running low or your fuel pressure is running high, a sign your filters need changing), etc. Our complete system is actually proprietary knowledge belonging to us and the company we worked with to do our vegetable oil conversion, but we are availale for consulting or installations. You can contact us here for details.
How much does a conversion cost?
It depends on the alternative diesel fuel system you want - how simplistic or complex of a system you want (meaning how much work you are willing to do over time, versus how much work you want to invest upfront). A good ballpark range is $3,000-10,000. Our first system was a very simple one and created a lot of extra work for us (such as manually heating and filtering veg, and manually transferring from a dirty tank that was not on the vehicle to a clean tank on the vehicle). Our system now is much more automatic, all done through a flip of a switch, but cost us about $10,000, a cost we recouped within about a year with our full-time travel.
Are there any drawbacks to using alternative diesel fuel?
The main drawback is that working with vegetable oil is a dirty job. It tends to get everywhere and you will certainly need dedicated "veg clothes" you don't mind ruining. If you're not inclined to engine work there may be a learning curve on learning how to change a filter or adjust the fuel pressure from time to time, and there is more time needed in finding waste veggie oil if you don't have a dedicated source. These are all things we've found easy to learn and handle, though, and can't see ourselves not running on alternative diesel fuel for some time to come.
Something you may need to consider is whether it's right for you, though. If you don't do a lot of driving, or all your driving is within a few miles of your home, the conversion won't be worthwhile as you'll be warming up or purging more than you'll be running on veg. Also if you live in a very cold climate you might find that it's difficult to keep the veg from solidifying, and so even when your engine is warm, your fuel might still be cold. This can be overcome with heating components, but it will mean added work and resources. So consider it carefully or contact us below for consulting.
Is waste vegetable oil sustainable?
No, it's not truly sustainable option to alternative diesel fuel. It's a great interim solution to use a waste product to decrease emissions and save resources, but ultimately WVO relies on a VERY unsustainable system: namely the fast food industry. I also feel that these restaurants might get wise to biodiesel and start saving and reusing their own oil for their own fleets, which would not at all be a bad idea for them, but would drastically reduce the availability for individuals to make use of the system now. We'll continue using the system while we can, but I really don't believe it can be sustained forever.
Do you do offer vegetable oil conversion or consulting?
No, but we recommend you do some Googling to find a shop near you that does. It is likely to require some travel (it's not often available) but it'll be worth making the trek.