Obtain approximately 4 gallons of used motor oil.
Bring to a boil the 4 gallons of motor oil. As it comes to a boil add 1 pint of Liquid Silicate of Soda.
Stir for approximately 10 minutes while boiling.
Let it settle until it is clear.
When the oil becomes cool enough and safe enough to mess with Remove the oil from the top. (Sediment and sludge will be at the bottom) Avoid tipping the container to such an extent as to stir up the sediment. Discard the sludge at your recycling center. The rest is good as new. I use it in my vehicles, lawn mower and tractor.