I did a write up on the Greasel conversion I did for my truck starting at 40,000 miles when I had it converted, to 100,000 which was a week or two ago, and all the things I have done to modify the process along with lessons learned. I posted it at Black-Rifles.com.
Polar Bear has it pretty well described, but I would differ with him on one very important point, filtration. If you don’t pre-filter the oil down to one or two microns you will clog your vehicle filters in short order, like a few hundred miles. Also, excessive engine wear can occur because particles in the sub-micron to 2 micron range typically do the most damage. Gas stations filter down to 30 microns normally, but they can do that because they are using distilled low viscosity fuels that sit still so they can settle most particulates. Oil is thick and will suspend small particles for a very long time. I filter my oil to one micron before it goes into my tank, and then again through two vehicle filters as I drive.
Also it is necessary to have a lift pump serving the oil tank. You can use the regular vehicle pump, but it puts a lot of strain on it, and it was never designed for that load. Having a lift pump hooked to the fuel selector switch means you have a second pump pushing as the regular pump pulls. I use a pump from F.A.S.S. that came with a 6 year warranty, which is unheard of.
Immediately after [Hurricane] Katrina, which was before my veggie conversion, I drove to Slidell, Louisiana with my brother in law to help him put his roof back on. I had underestimated the situation, and ended up having to buy 7 gallons of Crisco [cooking oil] at a Wal-Mart in Mississippi. As I was loading up my shopping cart a lady asked me if I was having a fish fry. I said, “No ma’am. This is fuel for my truck.” She got a soft, pitying look on her face, patted my arm, and said, “Sure it is honey.” [JWR Adds: Now that qualifies as s genuine SurvivalBlog moment!]
Remember, in a pinch, you can dump [clean vegetable] oil into a standard tank to mix with diesel and it will run fine. This works best in hot weather of course, but if your truck has a heated return line it will keep the fuel at about 115 degrees F, so you can do this in cold weather as well.
Since the conversion I can run my truck on:
Home heating fuel
Jet fuel [JP4]
Kerosene — preferably mixed with one gallon of vegetable oil to each 10 gallons of kerosene [to provide lubrication, since kerosene by itself is insufficient]
Or any mixture of the above
The conversion allows me to drive for 10 cents a gallon. 10 cents is roughly my cost after filtration. I can take $3 and drive for 17 miles on pump diesel, or I can take $3 and drive 510 miles on vegetable oil. That being said, the conversion was never about saving money, even though the conversion has paid for itself repeatedly now. The conversion was always about fuel flexibility in a pinch.
One last thing, Polar Bear states that there is a power drop when he transitions to vegetable oil. I don’t have that problem, but then I use a lift pump, so fuel delivery stays strong for me.
Thanks for taking the time to let me ramble to you again, – Jeff P.