I am a little confused about the temperature control during the mixing of Felix Lube. Folks talk about heating Mineral oil and caster oil til it smokes (300+ Deg F range) yet using a double boiler. Seams like a double boiler won't heat your oil up to those temps. Water boils at 212. Or do you use direct heat up til the point that you add the bees wax. Or am I missing something?