Art Mechanica

Here's a summary of how vegetable oil can be used, when it’s appropriate or not appropriate, where it can be obtained, how much effort is involved in gathering and preparing it, and legal ramifications. The information isn't new, but has been gathered from vendors and web forums. It was researched toward possible use in my 2008 F-250, but is applicable to just about diesel-powered vehicle.

Executive summary: vegetable oil (or even biodiesel above 5%) cannot be used in a 2008 Ford diesel engine (or any 2008 vehicle) because of loss of warranty coverage, probable damage to the elaborate emissions systems leading to early and costly replacement, and poor results obtained with engines newer than 2003 (with few exceptions). Dodge sounds the most confident to break the 5% barrier, because government-spec biodiesel can run up to 50%, but its official line is hemmed in by the fact that most "public" biodiesel runs the gamut from champaign to swill.

Straight vegetable oil (SVO) can be used successfully in earlier models using the 7.3 liter diesel, but one usage limitation is important to keep in mind. Because of its high viscosity, it is not suited for use for short trips and around-town use where the engine barely has a chance to warm up. It is well suited for long trips, towing, and any other circumstances where the vehicle will be running for long periods of time without shutdown.

Why is 2003 the cutoff year for Ford? A diesel engine is a diesel engine and can burn nearly anything, but the 6.0 liter engine that succeeded the 7.3 was designed in preparation for much tighter Federal emissions standards due to roll in by 2007. This hinged on using fuel that contained only tiny amounts of sulfur. Called Ultra Low Sulfur Diesel, ULSD fuel was shown to not clog emissions hardware like particulate filters as quickly as conventional “low sulfur” diesel fuel. So ULSD in itself does not lower emissions – it only enables emissions hardware to be used. By Federal edict, emissions systems have to be warranted to last 125,000 miles, and to do that even with the new fuel, the engine must be able to sense certain exhaust filters clogging and automatically burn them clean using extra fuel to boost exhaust heat. They must also try harder to monitor temperatures and pressures within the engine, since emissions can be affected by a problem. Think “dominoes”.

Now, SVO fuel is not petroleum-based like diesel fuel, and although it actually burns cleaner and produces about the same power and fuel economy, it doesn’t burn with exactly the same characteristics as the USLD fuel used to develop and auto-maintain the emissions hardware. As a result, 6.0 and 6.4 diesels may experience shorter emissions gear lifespan, cause more trouble lights to come on due to seeing temperatures and pressures outside the norm, and experience more frequent exhaust “regeneration” cycles designed to clear the exhaust filters, hurting fuel economy.

The 7.3 produced up to 2003 is considered a good candidate for SVO since it does not have to attain better emissions and so lacks the elaborate and precisely monitored hardware used on later engines that are calibrated only for ULSD fuel. Diesel engines prior to the late 1980’s are usually not recommended because the fuel system components will dissolve in SVO and biodiesel.

Except for hot climates in the far Southwest, any vehicle converted to use SVO needs to actually remain a dual-fuel vehicle. That is, it needs to have an SVO fuel system added alongside the diesel fuel system. It’s typically a bed-mounted rectangular tank that looks like a toolbox and permanently steals 1 to 1-1/2 feet of bed space behind the cab. This dual-fuel system is used because SVO is so much thicker than diesel fuel and requires heat to thin out enough to use. If you were to simply pour SVO into the existing tank, the engine’s fuel injectors probably wouldn’t be able to spray it into the combustion chambers to start up. At temperatures below 50 degrees F, SVO gels solid. Pumps can’t pump it, and injectors can’t inject it. Worse, less desirable types of SVO gel below 110 degrees. Regardless, in actual use the engine must always be started with diesel fuel before switching to SVO, and then switched back to diesel prior to final shutdown lest there be any SVO left in the system at the next restart. Otherwise, there wouldn’t be a restart.

To make the SVO flow and inject more like diesel fuel, anti-gel additives are used but have limited effectiveness. The primary fix is heat. The large SVO fuel tank is heated electrically, though often also with hot engine coolant. A large fuel filter in the engine bay is heated with engine coolant, and in many kits the fuel hoses are coolant-heated as well. The biggest determiner of when the SVO can be switched into use is the engine temperature itself. In cold weather, the Ford can take fifteen minutes or ten miles to reach normal temperature, then lose a lot of that heat in a one hour stop. Determined SVO fuel users in Wisconsin and Michigan line their SVO tanks and pipes with thick foam insulation, since the vehicle’s electrical system has only so much energy available for electric tank heaters – commonly just 300 watts maximum. The time needed to warm 15 or 40 gallons of SVO to be able to flow through a pipe is considerable, and garaging the vehicle is considered essential. Switch over to the SVO system too early, and the engine could stall with congealed SVO in the injectors – not good. The engine internals can develop heavy deposits as well. Proper use is essential.

Another limitation is that the SVO needs to be non-hydrogenated and fresh. Non-hydrogenated vegetable oil is a clear amber and flows well at room temperature. Hydrogenated vegetable oil is whitish and solid at room temperature. The user must also avoid spoiled oil, which typically has foam at the top, shows bacteria growth, and smells rotten. This will clog filters in no time. Water contamination is also fairly common. Oil used to cook breaded food is also to be avoided since the flour can quickly plug filters during the later cleaning stage. So, oil from KFC would be a last choice unless it has previously been proven to filter without big problems.

When gathering vegetable oil, the user typically deposits it into a large tank or drum in his garage, pouring it in from portable plastic containers. Here it is allowed to settle for a few days to let any water and food contamination fall to the bottom. Water ruins injectors. The rest is then drained or pumped out through fine filters into the vehicle tank or a bulk holding tank ready for use. Because flow through filters is slow, this process can be time consuming using gravity. A biocide is often added to slow bacterial growth. Good filtering is essential, because anything not caught now will simply wind up in the vehicle’s small, fine onboard filters. Clogs there can strand you on the road and cost more to replace. One SVO user has estimated that he spends 10-15 hours/week gathering and cleaning enough fuel to meet his car’s needs, so besides the “free” cost aspect of using SVO, it’s also a labor of love.

Users who have lined up a series of high quality sources can afford to pump fuel from the source directly into the onboard SVO fuel tank. This is done using a suction head tied to a 12V pump, and the oil is heated and forced through one or two fine filters before it gets to the tank. Filling can be somewhat leisurely due to the filters and the modest strength of the pump. Because availability schedules may not line up, direct filling doesn’t mean that temporary bulk storage isn’t needed for a cushion, but oil sources who aren’t depending solely on you for pickups are more appropriate. Despite a heater in the pump, trying to transfer fuel at temperatures below 50 degrees is considered an invitation to problems. I haven’t yet found out how people in Northern climates deal with winter collection. They may instead be collecting excess during summer and drawing from large bulk tanks kept in heated sheds or garages. Otherwise, the use of SVO is limited to being a seasonal hobby that’s abandoned in cool weather. That extends payback time. The vehicle can still be used of course, but is running on ordinary diesel fuel.

Vegetable oil is often collected from local restaurants. It is important to determine whether they use non-hydrogenated oil, and sometimes they don't know. Restaurants are often reluctant to talk with you until they understand why you want their waste oil and what you want it for. If appropriate, point out your vehicle and show them the system. As with anything else, be friendly, polite, and helpful. It's all about relationships, not weaseling free oil. Anything you do to make it simple for them, like leaving containers to fill, avoiding the lunch or dinner rush, or being available whenever they call, helps gain acceptance. They no longer have to pay to dispose of oil, but if you are lax about showing up when agreed, they then have a problem and will be reluctant to keep dealing with you. Good sources of oil are important, since you can become familiar with what they produce and may avoid having to settle out water and major food contaminants. There is less for you to deal with and dispose of. People who tend to drive a set number of miles a week on SVO and thus know how much they need have the easiest time of setting up a set route for pickups.

Other sources of oil are oil suppliers who occasionally need to get rid of off-spec oil, and snack food manufacturers who make fried foods. In these cases however, you often have to be able to cart away huge volumes in one shot – 1,000-5,000 gallons. At about 8 pounds/gallon, even the mighty F-250 with optional heavy duty springs can only manage 375 gallons in a load to hit its 3,000 pound specified limit. It has been claimed to handle 4,000 pound (500 gallon) loads, but the top-heavy nature of such filled tanks would make smooth driving and a rear anti-sway bar critical. Because of the bulk and weight of the large poly tank, the collection vehicle for such pickups loses its utility as a pickup truck – it’s now a dedicated tanker truck. You’d have to have a way to hoist the emptied tank out of the bed to be able to use it for anything else.

That brings us to the range issue. A very few heavy users of pickups fit extra SVO tanks to their trucks in the same way that normal diesel users do, or they mount one large agricultural tank. Whether in the bed or between the frame rails alongside the factory tank, they are the only ones who can venture well away from home base without resorting to diesel. Extra tanks can only be heated with engine coolant since there is no more electrical power to spare, but in highway use in moderate temperatures, a range of 1,300 miles just on SVO becomes fairly easy.

As for legality, the EPA has neither approved nor disapproved SVO as a motor fuel. Nobody has submitted it for emissions testing and approval of course, so until it is actually outlawed or approved, it isn’t a worry. The rendering trade, who processes SVO as an animal feed supplement, intensely dislikes the idea of scroungers taking their stock and robbing them of pickup fees, but have not yet done much about it other than complaining to state revenue authorities about people not paying fuel taxes on it. Illinois now requires that home brewers of biodiesel and SVO log collections and pay fuel taxes, and at least keeping a log is recommended just in case someone comes knocking. In Illinois, it doesn’t matter if the SVO is for your own personal use. The penalties are reportedly large.

The financial payback of installing an SVO kit is fairly quick, speeded up by the high rate at which fuel is used in a heavy pickup truck. A typical SVO kit with tank and various heated components plus a semi-automated switchover control costs about $2,600. A heated pump with filter for direct-to-tank filling costs $800. Filters are an ongoing cost, $20-30 for 5. One filter lasts for perhaps 200 gallons, and that varies with where you get your oil. For an F-250 that gets 13 MPG over the course of 10,000 miles/year, you’d pay back the $3,400 cost of the complete system somewhere over 850 gallons of SVO (11,050 miles worth at $4/gallon). That payback is slowed by how much diesel fuel was used in starting and shutdown, the cost of filters used, and any diesel fuel used in locally collecting the vegetable oil each week. One could say this last item is “free” when SVO is used to collect, but this driving, whether on diesel or SVO, wouldn’t occur if you were just living with filling up at the gas station instead. Buying fully-prepped SVO from fledgling outfits like Smartfuel (“Coming soon to Chicagoland!”) currently runs about $2.75/gallon, and was a dollar less a year ago.

Hydrogenated oils (the ones brimming with transfats) are in use because they stay “fresh” longer than non-hydrogenated oils. Because of health concerns, non-hydrogenated oils are suddenly becoming easy to find. As of early 2008, franchises that have claimed to have switched to non-hydrogenated oils are Wendy’s (corn & soybean mix), Ruby Tuesday (canola) Applebee’s, Denny’s, Bennigan’s, and Chili’s (soybean). Very low transfat oil (0.5%) is now claimed by Dunkin Donuts (palm, soybean, & cottonseed), Baskin Robbins, Starbuck’s, Arby’s, Hardee’s, TGI Friday’s, Taco Bell (canola), KFC, and Culver’s. McDonald’s has a history of claiming big non-hydro plans that fall through, so I don't trust them yet. Burger King claims by the end of 2008. Using oil from Dunkin' Donuts is iffy because of the potential amount of filter-clogging flour in it. KFC's breading can pose the same problem.

So, is using SVO and driving unlimited miles almost for free a practical thing? It depends on the user and his dedication to gather and process vegetable oil. When used as recommended in a pre-2004 vehicle, SVO has not been shown to cause any mechanical or performance problems in engines. When use is first begun, it will quickly clog onboard fuel filters because it aggressively cleans accumulated crud out of the fuel tank and lines, but that issue eventually goes away. SVO also slightly exaggerates the diesel’s basic characteristics: they suffer less problems and live the longest when they are used for hours at a time and used hard. Around-town park & shop is tough on a diesel, but more importantly prevents any practical switchover to SVO. You never get a chance. Forget to purge with diesel at shutdown, and you’ll be looking for a tow truck.

The other possible SVO vehicle could be a Volkswagen up to 2006, or an old Mercedes diesel. Mileage would at worst double over a pickup truck, decreasing the amount of SVO needed to gather (and also doubling payback time to at least 3 years). The only real caveat with using SVO in a passenger car or SUV is the presence of a heavy fuel tank in the trunk or passenger area. Naturally, the trunk space disappears forever. Plus, regardless of how it’s strapped down, the tank makes quite a battering ram in a bad crash, and a fuel leak from damaged lines into the car’s interior could make for a very unpleasant situation. Without a working trunk, gathering vegetable oil means that a direct-to-tank gathering system must be used (you open your trunk lid to fill), otherwise any portable containers must be carried in the back seat – not good considering that they won’t be pristine.

In the end, between the temperature restrictions and the work to gather and process, the seasonal limitations and inconveniences, the garage use for parking and winter fuel storage, the potential messiness, and the amount of free time you have, using SVO becomes a personal question. One final aspect enters in, though. If one is either suspicious or just plain paranoid that there may eventually be another 70’s-style oil shortage with purchase restrictions and long lines, or skyrocketing spot prices due to shortages, already having an SVO system set up and in use is the next best thing to having a plug-in electric car. Gas crisis? That’s where you and your wife fight over who gets to use the SVO vehicle. You wait in line for diesel only as much as you use diesel for starting and warmup. Everything else is highly available and free for the taking. Considering that crude oil prices are unlikely to do anything other than edge upward, SVO is still something to consider. It saves money in much the same way as gathering and preparing your own free firewood for an efficient heating stove. Like that endeavor, it’s a good amount of work.