INTRODUCTION
The idea for the Dr Pepper Technique came about one day many years ago (it seems) when I was trying to figure out an inexpensive way of making a few test batches of biodiesel.

WARNING
I will assume that if you are reading this for the information then you are new to Biodiesel making, so just a few words of caution:
- THESE ARE DANGEROUS/POISONOUS CHEMICALS
- COMMON SENSE MUST BE USED
- YOU ARE RESPONSIBLE FOR YOUR ACTIONS AND THE SAFETY OF YOURSELF AND
   EVERYONE/EVERYTHING AROUND YOU
- METHANOL IS A POISON WHICH CAN BE ABSORBED THROUGH YOUR SKIN, BY
   INHILATION, OR CONSUMPTION
- METHANOL CAN CAUSE BLINDNESS AND DEATH
- METHANOL IS AS FLAMMABLE AS GASOLINE/PETROL
- CARTRIDGE RESPIRATORS DO NOT WORK WITH METHANOL
- Sodium hydroxide (Caustic soda, NaOH, lye) can cause severe burns and death.
- Long-sleve shirt, full shoes and trousers are recommended, no shorts or sandals.
- Wear chemical proof gloves, apron, and eye protection.
- Do NOT inhale any vapors.
- Always have running water available to wash off any splashes.

Now that I have managed to scare you, just realize that Methanol is the fuel used in most model airplanes. In the USA methanol is available in small quantities as HEET brand fuel line antifreeze (Yellow bottle)
Lye is an every-day drain cleaner.
Both are freely available in most large shopping centres.

MATERIALS REQUIRED
1 litre oil- new or used
NaOH (lye / caustic soda), at least 6g.
   --Used as a drain cleaner and can often be found next to the Drano.
Methanol at least 250ml.
   --HEET® Gas- Line Antifreeze in the yellow bottle is methanol and readly available in most auto supply stores in the USA.

EQUIPMENT REQUIRED
1- 2 litre (1.9 in US) Dr Pepper Bottle in sound condition with top and dry inside.
1- measuring cup to measure out 250ml methanol
1- scale to measure 6g NaOH
    OR
1- teaspoon measure metric or imperial
1- container to mix the methanol and NaOH in which makes methoxide.
1- Funnel

THE TECHNIQUE

OIL PREPERATION
If using waste oil, take one litre and heat to at least 120 deg c to remove all water.
If water is present the oil will spit and pop and carry on.
If there is a lot of water this could get very violent, so be careful.

Once the water is gone (Oil becomes calm and there is no more spitting and popping) let the oil cool.

If you are using new oil from the bottle it should have no water in it, so in this case just heat to 55deg c when you are ready to mix.

MAKING THE METHOXIDE
WARNING:
METHOXIDE IS A POISON! DO NOT BREATH VAPORS. WASH OFF ANY SPLASHES.
DO NOT MIX THE METHOXIDE IN A PLASTIC SOFT DRINK BOTTLE AS THE NaOH ATTACKS THE PLASTIC AND YOU WILL QUICKLY BE SHAKING A BOTTLE FULL OF HOLES WITH METHOXIDE GOING EVERYWHERE.

While the oil is cooling mix your methanol and NaOH(lye) to form the methoxide. Use 250ml of methanol. This is more methanol than most people use but will help insure a successful first batch.
If you are using new oil this will require 4g (about half a Teaspoon) NaOH.
For used oil, you should do a titration to determine the correct amount of NaOH to use. However, if you do not have the materials to do a titration, just use 6g- 7g NaOH as this amount almost always works. If you do not have a scales, this is about 1 level teaspoon measure (metric or imperial).

NaOH and Methanol do not readily mix, so if you are doing it by hand a bit of time and patience is required. Don't sniff the fumes. CARTRIDGE RESPIRATORS DO NOT WORK WITH METHANOL

For quickest mixing, start with the methanol at JUST body temp (not warm). As you mix, the temp will increase substantially. This is normal. Make sure ALL the NaOH (lye) is disolved. This may take 10 minutes or more.

Hand mixing can be accomplished using a spoon to stir/crush the NaOH granules; OR placing methanol/NaOH in a glass bottle with a top and shaking/ swirling until ALL NaOH is disolved.

After ALL the NaOH has disolved, top up to 250ml with fresh methanol, as there may be some evaporation during mixing.

MAKING THE BIODIESEL!
When the Oil's temp has dropped to 60 deg c or less, using a funnel, pour the litre of oil into a DRY 2 litre Dr Pepper bottle (in a pinch any other brand of bottle will do).
Take the mixture of methanol/NaOH (commonly called methoxide on this forum) and pour on top of the oil using the same funnel.
Remove funnel.
Screw the top down TIGHT onto the bottle.
Shake vigerously for about ten seconds / 40 good shakes.
NO appreciable pressure is generated during this mixing.

Now place the bottle on a table and observe the oil change colour from a "Chocolate milk to a rich, darker brown."
Then, as if by magic, within 10 minutes the by-product (commonly refered to as glycerine on this forum) starts to settle out and form an increasing layer on the bottom of the bottle.

Within an hour, most of the glycerine will be settled out. This is referred to as seperation.
Be sure to notice that you can see a very definate, slowly sinking line towards the top of the Biodiesel as the glycerine slowly settles.

You should now have a bottle containing lighter coloured biodiesel on top of a layer of darker glycerine. The biodiesel will be very cloudy, and it will take a day or two more for it to clear.
Typically the glycerine layer is about the same or a bit more than the amount of methanol used.

ADDITIONAL COMMENTS
For an excellent in-depth article about making biodiesel, read Mike Pelly's article on biodiesel production.

Now that you have a Litre of Finest biodiesel you will probably wish to wash it and this is quite easily accomplished using the World Famous Dr Pepper Wash Technique (Pat Pend)