Okla. Stat. tit. 68 § 712
Every special fuel dealer using special fuel to propel any motor vehicle on the highways of this state and all special fuel users, including special fuel users who import special fuel into this state in the supply tanks of motor vehicles using the highways for commercial purposes, shall keep, in addition to the foregoing requirements as to records which apply to them, records of the mileage traveled by each and all motor vehicles propelled by special fuel using the highways of this state including the motor vehicles owned, operated, leased or under any other form of contract, together with inventories, withdrawals, deliveries, purchases supported by invoices, and such other records as may be required by the tax Commission. All such records and invoices must be preserved for a period of at least three (3) years.
Okla. Stat. tit. 68, § 712