Okla. Stat. tit. 68, § 68-712: Records of dealers and users

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.