EXHIBIT 5

                           ___________________, 1999

Plains Resources Inc.
Arguello, Inc.
Calumet Florida, Inc.
Plains Illinois Inc.
Plains Resources International Inc.
PMCT INC.
Stocker Resources, Inc.
Stocker Resources L.P.
500 Dallas Street
Houston, Texas 77002

Dear Sirs:

        I have acted as counsel for Plains Resources Inc., a Delaware
corporation (the "Company"), and the Subsidiary Guarantors (defined below) in
connection with the proposed offer by the Company to exchange (the "Exchange
Offer") for all outstanding 10 1/4% Senior Subordinated Notes Due 2006, Series E
($75 million principal amount outstanding) (the "Outstanding Notes") 10 1/4%
Senior Subordinated Notes Due 2006, Series F ($75 million principal amount) (the
"Exchange Notes"). The Outstanding Notes have been, and the Exchange Notes will
be, issued pursuant to an Indenture dated as of September 15, 1999, (the
"Indenture"), among the Company, the Subsidiary Guarantors and Chase Bank of
Texas, National Association, as trustee (the "Trustee"). Arguello, Inc., Calumet
Florida, Inc., Plains Illinois Inc., Plains Resources International Inc., PMCT
INC., Stocker Resources, Inc., and Stocker Resources L.P. are collectively
referred to as the "Subsidiary Guarantors", and the guarantees by the Subsidiary
Guarantors with respect to the Exchange Notes are collectively referred to as
the "Guarantees".

        In connection with such matters I have examined the Indenture, the
Registration Statement on Form S-4, filed by the Company with the Securities and
Exchange Commission, for the registration of the Exchange Notes and the
Guarantees thereof (collectively referred to as the "Securities") under the
Securities Act of 1933 (the Registration Statement as amended at the time it
becomes effective being referred to as the "Registration Statement") and such
corporate records of the Company and the Subsidiary Guarantors, certificates of
public officials and such other documents as I have deemed necessary or
appropriate for the purpose of this opinion.

        Based upon the foregoing, subject to the qualifications hereinafter set
forth, and having regard for such legal considerations as I deem relevant, I
am of the opinion that:

        (i)     The Company has been duly incorporated and is validly existing
                as a corporation in good standing under the laws of the State of
                Delaware;

        (ii)    Each of the Subsidiary Guarantors has been duly incorporated or
                organized and is validly existing as a corporation or
                partnership in good standing under the laws of the jurisdiction
                in which it is incorporated or organized; and

        (iii)   The Securities proposed to be issued pursuant to the Exchange
                Offer have been duly authorized for issuance and, subject to the
                Registration Statement becoming effective under


_____________, 1999
Page 2

                the Securities Act of 1933, and to compliance with any
                applicable state securities laws, when issued, delivered and
                sold in accordance with the Exchange Offer and the Indenture,
                will be valid and legally binding obligations of the Company and
                the Subsidiary Guarantors, enforceable against the Company and
                the Subsidiary Guarantors in accordance with their respective
                terms.

        The opinions expressed herein are subject to the following:

        --  The enforceability of the Securities may be limited or affected by
            (i) bankruptcy, insolvency, reorganization, moratorium, liquidation,
            rearrangement, fraudulent transfer, fraudulent conveyance and other
            similar laws (including court decisions) now or hereafter in effect
            and affecting the rights and remedies of creditors generally or
            providing for the relief of debtors, (ii) the refusal of a
            particular court to grant equitable remedies, including without
            limitation, specific performance and injunctive relief, and (iii)
            general principles of equity (regardless of whether such remedies
            are sought in a proceeding in equity or at law).

        --  I express no opinion as to the enforceability of any provisions of
            the Securities that would require the performance thereof in the
            presence of fraud or illegality on the part of the holders of the
            Securities or the Trustee.

        The opinions expressed herein are limited exclusively to the laws of the
State of Texas and the General Corporation Law of the State of Delaware.

        I hereby consent to the filing of this opinion as an Exhibit to the
Registration Statement and to the reference to me under "Legal Matters" in the
Prospectus forming a part of the Registration Statement.

                                               Sincerely,

                                               /s/   Michael R. Patterson

                                               Michael R. Patterson
                                               Vice President & General Counsel