This article does not preclude subordination by agreement by a person entitled to priority.
Okla. Stat. tit. 12A, § 1-9-339
Oklahoma Code Comment
Pre-code Oklahoma law was the same. Kirkpatrick v. Oil Well Supply Co., 172 Okl. 248, 49 P.2d 712 (1935). A subordination agreement will affect the relative priorities of the parties to it. It will not, however, affect the rights of non-parties. Wilmot v. Central Oklahoma Gravel Corp., 620 P.2d 1350 (Okl. 1980). The subordination agreement need not be in any particular form. It can even be oral. Williams v. First National Bank & Trust, 482 P.2d 595 (Okla. 1971). Subordination of an interest in the collateral will also subordinate the interest in the proceeds. Anderson, Clayton & Co. v. First American Bank of Erick, 614 P.2d 1091 (Okla. 1980).