Okla. Stat. tit. 62 § 435
(Application.) Such sinking funds shall be used:
First. For the payment of interest coupons as they fall due.
Second. For the payment of bonds falling due, if any such there be, and,
Third. For the payment of judgments against the municipality, if any there be; provided, that when any sinking fund has been used or may hereafter be used to pay judgments as herein provided, that notwithstanding the fact that such judgment or judgments have been paid with such sinking fund, it shall be the duty of the proper officers to make levies to pay such judgments the same as if the same had not been paid out of such sinking fund, and when so levied and collected the same shall be turned into the sinking fund out of which such judgment or judgments was paid.
Okla. Stat. tit. 62, § 435