Every distributor, manufacturer, retail dealer, or storer of lubricating oil, as herein defined, shall pay an excise tax of $.02 per gallon upon the selling, distributing, or withdrawing from storage in this state for any use lubricating oil as herein defined; provided, that this excise tax shall neither be levied upon the sale of lubricating oil in interstate commerce nor upon any sale of lubricating oil destined for out-of-state use which is transacted in a manner whereby an out-of-state purchaser takes delivery of such oil at a distributor's plant within this state and transports it out-of-state; and provided further that this excise tax shall not be levied on lubricating oil sold to city and county governing bodies, city and county boards of education, the Alabama Institute for Deaf and Blind, the Department of Youth Services school district, and private and church schools as defined in Section 16-28-1, and which offer essentially the same curriculum as offered in grades K-12 in the public schools of this state; and provided further, that where the excise tax of $.02 per gallon upon the sale of the lubricating oil shall have been paid by a distributor, manufacturer, retail dealer, or storer, payment shall be paid but one time by any person so liable. The state Department of Revenue is hereby authorized to issue to the United States certificates of exemption, upon forms prescribed by the department, for use by the United States in purchasing lubricating oil within the State of Alabama and which is paid for by the United States. Any person in reporting and paying the tax to the department may deduct the number of gallons of lubricating oil so sold to the United States, as shown by the certificates of exemption duly executed by the United States and filed with the report. The department is authorized to adopt rules and regulations with respect to the issuance and use of the certificates.