how much liquid KOH for 40 gallons of oil do I need to make biodiesel if my titration is 6.25 grams per lit er? janmer8

You can't use liquid KOH. You need flake or beads (NaOH). The liquid stuff is a solution of the caustic in water. Water kills the transesterification reaction.

Hi Janmer8,

If you can get hold of some flakes or "pearl" beads of KOH, add them to your Methanol as you would NaOH. Remember the purity of your KOH may/will be different to that of NaOH - so check with supplier. NB: KOH is slightly more water tolerant but it still cant be used in an aqueous solution.