{short description of image}


Vegetable oil will react very similarly to diesel fuel under the conditions inside a diesel engine; i.e. when it is highly compressed, it will heat up and ignite, causing the air in the cylinder to expand, and to push the pistons, in time. If you burned straight unprocessed vegetable oil, however, the fatty acids in the oil would start to congeal and harden (coke up) on the inside of your engine as well as in your fuel injectors, eventually leading to big, expensive engine problems.

Therefore, it is necessary to process your oil to remove the fatty acids-- making the oil more similar to diesel compositionally, or to otherwise devise a system to keep your engine clean of residues from unprocessed oil.

Following is our procedure for edible waste oil transesterification, which we used on our cross country trip. Please always use extreme caution when working with these ingredients.


-We are not automotive engineers, chemists nor scientists of any type so this information is still in a crude, explorative stage. Experiment to find what works for you.

-This information was collected from various individuals and has been used by us BUT by no means do we hold any responsibility for anyone attempting to do this process. Essentially this is public information to be used at your own discretion and risk. There is information available regarding transesterification and biodiesel. It is highly recommended to cross-reference and /or to contact someone in the organic chemistry department at a local university.

-This information shall not be resold to any individual but given freely to all who may inquire about this procedure.

-Methanol is toxic. It can be absorbed by the skin and cause nerve deterioration with prolonged usage. If splashed in eyes it can cause blindness and could be fatal if swallowed. Take necessary precautions when using methanol! A good respirator and decent rubber gloves are recommended.

-Lye is also very toxic and burns the skin upon touch. It is also extremely damaging if ingested. It is possible, however to set up a safe means of being able to mix fuel. An outdoor area is preferable or a space with plenty of ventilation. Access to electricity and water are both necessary. Have lots of newspapers and detergent on hand.

-Always mix a small batch first in an old blender to test your ratios. If successful the amounts can be multiplied directly.


Production of Biodiesel for Diesel fuel use

You will need:
  • Used or fresh vegetable oil (strained with a coffee filter or cloth)
  • Red Devil Lye
  • Methanol (dry gas methanol-- we found it at automotive racing stores)
  • Isopropyl Alcohol (for tests-- use 99% IPA)
  • eyedropper- or other type of 1 milliliter dropper
  • PH paper-- available at drug stores-- to test for acidity
  • an old blender
  • plastic or glass measuring cups or beakers, with metric measures-- and/or a gram scale
  • plastic, glass or stainless stirrers and spoons,
  • plastic buckets
  • rubber gloves, safety glasses, plastic apron

Titration Process to determine how much Lye to use

Free fatty acids will increase with the amount of time vegetable oil has been heated-- oil which has been used for cooking will require more of the reactive agents-- lye and methanol-- than fresh oil. The presence of too many free fatty acids will retard or stop the reaction which produces biodiesel, so it is necessary to detect the exact amount of LYE (Sodium Hydroxide-- or NaOH) needed to neutralize the acids. Adding too much or too little NaOH will just make excessive amounts of bi-product (soap).

  1. Dissolve 1 gram NaOH (Sodium Hydroxide- Red Devil Lye) in 1000 ml. of water. This is your NaOH solution.
  2. Dissolve 1ml. of Wasted Vegetable Oil (WVO) in 10 ml. Isopropyl Alcohol(IPA). This is your WVO solution.
  3. With an eyedropper, drop the diluted NaOH into WVO mixture a milliliter at a time. Count the drops. After each ml drop check the ph level of the WVO solution with standard ph paper-- you will see an eventual rise in the ph level. Continue to add the NaOH solution into the WVO solution, a drop at a time, until it reaches a ph of 8-9.

To determine your proportions, figure:

The number of drops of NaOH needed for the WVO solution to reach a ph of 8-9 1 ml. plus 3.5 g. NaOH to catalyze the oil

An example formula used with one particular batch of WVO-wasted vegetable oil.

1 ml of oil was titrated with a 1g NaOH/1000 ml H2O solution.

It required 6.0 ml to raise the ph level to 8 = .006g

 so	      6.0g/1000ml to neutralize the free fatty acids 

 plus	      3.5 g NaOH as catalyst 

          =   9.5 g per 1000ml oil or 9.5g/915g oil=103% by wt.

Transesterification For Wasted Vegetable Oil (WVO)

Vegetable Oil: Diesel has a chain of 11-13 carbons, and new vegetable oil has a chain of about 18--but wasted vegetable oil-- which has been heated--has chains of up to 32 carbons. To burn in an engine, the chain needs to be broken down to be similar in length to diesel

Lye: (Sodium Hydroxide ((NaOH)-- or potassium hydroxide also works) is the catalyst for transesterification. It works by "cracking" the vegetable oil molecules, splitting the triglycerides from the hydrocarbons and shortening the carbon chain. (3.5g or .35% is the standard amount of lye necessary to create a reaction, when using fresh vegetable oil, so you can figure that used vegetable oil will always use more.)

Methanol: The amount of methanol needed will also vary, but the ideal is to use the least amount of methanol necessary in order to get the highest yield. The yield is related to completion; so if you get a 90% yield that means that 90% of the fatty acids have been eliminated from the vegetable oil. We have found that the best is to use 15% to 20% methanol, based upon the total weight of your batch of oil.
*it is best to use dry gas methanol (we found methanol at an automotive racing store)

A hydrometer can also be used to check the amount of completion according to density

  • Vegetable Oil has a specific density of .910
  • Biodiesel has a specific density of .850-.870

Recipe for Colorado Gold example test

-- using WVO we got in Colorado

  1. Weigh 4kg of WVO heated in a stock pot on a hot plate up to 120F degrees
  2. In separate container mix-15%of 4Kg=600g Methanol (MeOH)* (or 17.2% by volume=750ml) with-
  3. 40g (1%) of NaOH until the NaOH dissolves. Add the NaOH slowly! It will become extremely hot, and on a larger scale potentially dangerous.

This combined mixture makes Sodium Methoxide. Add this to the WVO and mix for 40-60 minutes. We used a dry wall mixer bit attached to a 1/2 foot drill to do the mixing

NOW---Draw out samples every 5-10 minutes to check the rate of separation. The cloudy looking free fatty acids, called glycerine, will sink to the bottom and the methyl esters--a translucent liquid, will remain on top. When the separation appears not to be advancing any more, stop mixing. Let the mixture settle for at least 8 hours.

The liquid you have on top now is methyl ester, but before using it you have to remove any remaining soaps or salts which could cause engine damage . The glycerin which has sunk to the bottom should be disposed at your local toxic waste disposal site.

RINSING METHYL ESTER: Pour off the methyl ester into a separate clean container, so it can be washed free of any remaining soaps, salts or free fatty acids.

Add water to the methyl ester. Stir slightly and then allow mix to settle. When the water has cleanly separated from the methyl esters, drain or pump the water out from the bottom. Repeat until the discarded rinse water reaches ph level of 6-7 -- and no soap bubbles appear.

If the liquid is cloudy, there is water being retained in the fuel, and it will need to be reheated slowly to evaporate out the water. Any white substances forming at the bottom or any bubbles forming at the surface is a sign of soaps and should be removed or the liquid should be re-washed. The cleaned methyl esters are now a homemade version of biodiesel and are ready to go into your diesel tank.

ONE MORE WARNING: To use 100% Biodiesel for longer than 4 weeks straight will cause complications to any rubber components of the engine that the fuel might come into contact with-fuel pump, hoses, o-rings, etc. These can either be replaced with steel or heavy duty rubber or.. it is recommended to use a percentage of diesel with your homemade fuel- at least 20%.