Okla. Stat. tit. 68 § 716
Every person acting as a special fuel dealer who sells and delivers any special fuel, as defined in this act, into the fuel supply tank or tanks of any motor vehicle in this state must, at the time of such delivery, make and deliver to the person owning or operating such vehicle (the purchaser of such fuel or his agent) an invoice covering each such delivery, showing the name of the operator or purchaser, the date, the name and address of the special fuel dealer and his special fuel dealer's license number, the number of gallons of special fuel delivered, the place of delivery, the correct name of such fuel, the price per gallon and total sale price of the amount delivered, and such other information as the Commission may require. Each such invoice must be made in duplicate, be identified by consecutive numbers printed thereon, and each special fuel dealer must furnish said invoices and retain one copy thereof and be able to account for each numbered delivery invoice and each copy thereof.
The invoices required by this section must be demanded by every person purchasing and receiving a delivery of special fuel into the supply tank of a motor vehicle in Oklahoma at the time of such delivery and such person shall carry any such invoice with the vehicle until the fuel covered by same is consumed. If the special fuel is delivered by a licensed dealer or user into the supply tank or tanks of his own vehicles, a notation or proper record of same shall be made on the invoice.
Every person making such sales and deliveries of special fuel and every person so receiving and purchasing special fuel must each retain one copy of each such invoice as a part of his permanent records for a period of at least three (3) years.
Every special fuel dealer or user who shall make any delivery of special fuel into the supply tank of any motor vehicle owned and operated by such dealer or user shall make and maintain for at least three (3) years a record of all such deliveries of special fuel showing such information as the Commission may require.
Okla. Stat. tit. 68, § 716