Okla. Stat. tit. 23, § 23-26: Breach of covenants against encumbrances

The detriment caused by the breach of a covenant against

encumbrances in a grant of an estate in real property, is deemed to

be the amount which has been actually expended by the covenantee in

extinguishment of either the principal or interest thereof; not

exceeding in the former case a proportion of the price paid to the

grantor, equivalent to the relative value, at the time of the grant,

of the property affected by the breach, as compared with the whole;

or, in the latter case, interest on a like amount.