Okla. Stat. tit. 46, § 46-13: Assignments of existing mortgages - Recording within four

months - Mortgages on record for six months.

All assignments of mortgages at present existing, bearing date

prior to the taking effect of this act, shall within four (4) months

next succeeding the taking effect of this act be recorded in the

proper county of this state, in accordance with the provisions of

Section 1, of this act, whether such assignments be acknowledged or

not, and in case such assignments are not recorded within the time

herein provided, the payment of any interest or principal on the

debts secured by such mortgages to the mortgagees or the assignees

whose assignments appear last of record after the expiration of the

time herein provided, and before the recording of such assignments,

shall be and constitute a complete defense to any action on such

mortgage or note or other evidence of indebtedness secured thereby

as against the mortgagor, his heirs, personal representatives, or

assigns: Provided, however, that the last assignee of an unrecorded

assignment shall have a right of action against the assignor to whom

such interest or principal is paid; and provided further, that where

the mortgagor, his heirs, personal representatives, or assigns have

actual notice or knowledge of such assignment or transfer, then in

such case such payment shall constitute no defense, and none of the

provisions of this act shall apply. Provided, this section applies

only to mortgages which have been on record six (6) months or more.