Okla. Stat. tit. 68, § 68-703: Imposition of tax

(a) There is hereby levied and imposed an excise tax of five and

one-half ($0.055) cents per gallon on the use, within the meanings

of the word "use" as defined in this act, of all special fuels

delivered in this state into the fuel supply tank or tanks of motor

vehicles. The delivery or placing of special fuel into the fuel

supply tank or tanks of motor vehicles for use in whole or in part

for power to propel such vehicles on the public highways shall

constitute and is hereby declared to be the taxable incidence of

this levy.

(b) An excise tax of five and one-half ($0.055) cents per gallon

is also levied, in consideration of the use of the highways of this

State, on the use of all special fuels imported into Oklahoma in the

fuel supply tank or tanks of motor vehicles and used to propel said

motor vehicles for commercial purposes, public or private, or for

transportation for hire or compensation, on the public highways of

this state, which tax shall be measured and determined by the number

of gallons of such imported special fuels actually used in Oklahoma.