The excise tax imposed by this article shall apply to persons, firms, corporations, dealers, or distributors storing lubricating oil and distributing the same or allowing the same to be withdrawn from storage, whether such withdrawals are for sale or for use; provided, that “sellers” of lubricating oil and its substitutes paying the tax herein provided may pay the same computed and paid on a basis of their sales as hereinafter required, and storers and distributors shall compute and pay this tax on the basis of their withdrawals or distributions.