p#H# refers to the relative concentration of #H^+# and #OH^-# in aqueous (water-based) solution, and does not really apply to oils.
Explanation:
As pointed out, p#H# does not really apply to non-aqueous solutions. Oils can entrain water, which (or so am I told) can support concentrations of hydrogen sulfide, which can act as a weak acid in water. Other than this you are going to have to find a better informed specialist.