TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The method further comprises: mixing the content of the used oil, the second catalyst and the alcohol vigorously to produce a biodiesel and a glycerin; removing the glycerin and the alcohol; washing the biodiesel with a water spray in a chamber; removing the water using at least one of a water adherent and a water absorbent; estimating an ASTM number for the end product biodiesel; and using the biodiesel as a fuel for a vehicle. The predetermined time for adding the second catalyst is 4-7 minutes and the adding of alcohol is 3-6 minutes in the adding process in sequence. The predetermined time for adding the second catalyst potassium hydroxide and the alcohol methanol in the adding process simultaneously is 15 minutes. The method further comprises: settling the oil for a predetermined time prior to using for biodiesel production; removing sediment and water from the used oil prior to heating to a predetermined temperature; reacting with sodium methylate prior to mixing with the second catalyst and the alcohol; and removing the glycerin and estimating the glycerin value number by titrating to estimate the ratio of second catalyst and the alcohol. The temperature is 138 degrees F. The predetermined time duration for adding second catalyst is 5 minutes, where the second catalyst is potassium hydroxide. The predetermined time for adding the alcohol is 4 minutes and the alcohol is methanol. The potassium hydroxide is added first and methanol is added later to the used oil. The method further comprises: mixing a factor determined by the glycerin value multiplied by 20% of glycerin value as the content of the second catalyst; and adding the second catalyst and the alcohol to the used oil mix to get a biodiesel of low ASTM value. The method further comprises: removing the methanol from the biodiesel prior to washing; washing the biodiesel through a water spray; and removing the water by passing through three different chambers to remove water to make biodiesel. Preferred Components: The amount of the used oil to second catalyst is equivalent to a total of a glycerin value number in gallons multiplied to 20% of the glycerin value number in gallons, where the amount of alcohol in gallons is equivalent to a second catalyst in gallons added to the glycerin value number in gallons. The first catalyst is at least one of sodium methylate, sodium hydroxide and sodium methoxide, the second catalyst is potassium hydroxide and the alcohol is methanol. The ASTM number is 0.07-0.25, preferably 0.08. The second catalyst is potassium hydroxide and the alcohol is methanol. The ASTM value is 0.07-0.25. The glycerin value is 0.65, the potassium hydroxide amount is 80 gallons and the methanol is 220 gallons for the used oil amount of 4600 gallons.