As a motor oil "treatment," I assume the pale oil is primarily a diluting carrier for the naphtha solvent (although I know that mineral/baby oil is. Pale Oil. Restores silks and protects leathers while you clean. Conditions and softens leathers and suedes. Restores luster and depth of color to silks and other . Pale Oil, or Heavy distillate (diesel), is as put just diesel. The smoke that is created is the fact that a gas engine doesn't burn diesel very well.