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                                                                   EXHIBIT 10(v)


                               SIXTH AMENDMENT TO
                  THIRD AMENDED AND RESTATED CREDIT AGREEMENT

     THIS SIXTH AMENDMENT TO THIRD AMENDED AND RESTATED CREDIT AGREEMENT (this
"Amendment") dated as of the 10th day of February, 1998, by and among PLAINS
RESOURCES INC., a Delaware corporation (the "Company"), ING (U.S.) CAPITAL
CORPORATION, f/k/a Internationale Nederlanden (U.S.) Capital Corporation, as
Agent ("Agent"), and the Lenders under the Original Agreement (as defined
herein).

                              W I T N E S S E T H:

     WHEREAS, the Company, Agent and Lenders entered into that certain Third
Amended and Restated Credit Agreement dated as of April 11, 1996, as amended by
that certain First Amendment to Third Amended and Restated Credit Agreement
dated December 16, 1996, that certain Second Amendment to Third Amended and
Restated Credit Agreement dated March 7, 1997, that certain Third Amendment to
Third Amended and Restated Credit Agreement dated July 18, 1997, that certain
Fourth Amendment to Third Amended and Restated Credit Agreement dated August 29,
1997 and that certain Fifth Amendment to Third Amended and Restated Credit
Agreement dated November 3, 1997 (as amended, the "Original Agreement") for the
purposes and consideration therein expressed, pursuant to which Lenders became
obligated to make and made loans to the Company as therein provided; and

     WHEREAS, the Company, Agent and Lenders desire to amend the Original
Agreement for the purposes described herein;

     NOW, THEREFORE, in consideration of the premises and the mutual covenants
and agreements contained herein and in the Original Agreement, in consideration
of the loans which may hereafter be made by Lenders to the Company, and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties hereto do hereby agree as follows:

                    ARTICLE I. -- Definitions and References

     (S) 1.1.  Terms Defined in the Original Agreement.  Unless the context
otherwise requires or unless otherwise expressly defined herein, the terms
defined in the Original Agreement shall have the same meanings whenever used in
this Amendment.

     (S) 1.2.  Other Defined Terms.  Unless the context otherwise requires, the
following terms when used in this Amendment shall have the meanings assigned to
them in this (S) 1.2.

     "Amendment" means this Sixth Amendment to Third Amended and Restated Credit
     Agreement.

     "Amendment Documents" means this Amendment.
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     "Credit Agreement" means the Original Agreement as amended hereby.

                           ARTICLE II. -- Amendments

     (S) 2.1.  Definitions.  The definition of "Subsidiary" set forth in Section
1.01 of the Original Agreement is hereby amended by adding the following
sentence at the end thereof.

     Notwithstanding the foregoing, pursuant to Section 8.35 no Unrestricted
     Subsidiary shall be deemed a "Subsidiary" of the Company for purposes of
     this Agreement and each other Basic Document.

     The following definition of "Unrestricted Subsidiary" is hereby added to
Section 1.1 of the Original Agreement immediately following the definition of
"Type":

     "Unrestricted Subsidiary" shall have the meaning given it in Section 8.35.

     (S) 2.2.  Use of Proceeds.  Section 8.17 of the Original Agreement is
hereby amended by adding a new sentence at the end thereof, to read as follows:

     In addition, the Company may use up to $40,000,000 of the proceeds of the
     Loans hereunder to make capital contributions to Unrestricted Subsidiaries
     as permitted in Section 8.10(e).

     (S) 2.3.  Investments.  Section 8.10 of the Original Agreement is hereby
amended by renumbering current subsection (e) and (f) as (g) and (h),
respectively, and adding new subsections (e) and (f), to read as follows:

     (e) capital contributions to Unrestricted Subsidiaries from time to time in
     an aggregate amount not to exceed $40,000,000;

     (f) in addition to any capital contributions permitted in subsection (e)
     above, capital contributions to Unrestricted Subsidiaries of up to
     $70,000,000 of the proceeds of any capital stock of the Company issued
     after January 1, 1998;

     (S) 2.4.  Unrestricted Subsidiaries.  Article VIII of the Original
Agreement is hereby amended by adding a new Section 8.35 at the end thereof, to
read as follows:

     Section 8.35  Unrestricted Subsidiaries.  The Company may form one new
     subsidiary, which may be in the form of a corporation, partnership, limited
     liability company or other business entity (such new subsidiary, and each
     of its subsidiaries, each an "Unrestricted Subsidiary"), which Unrestricted
     Subsidiaries shall be subject to the following:

     (a)  Subject to subsection (d) below, no Unrestricted Subsidiary shall be
          deemed to be a "Subsidiary" of the Company for purposes of this
          Agreement or any other Basic Document, and no Unrestricted Subsidiary
          shall be subject to or included within the scope of any provision
          herein or in any other Basic Document, including without 
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          limitation any representation, warranty, covenant or Event of Default
          herein or in any other Basic Document, except as set forth in this
          Section 8.35.

     (b)  Neither the Company nor any of its Subsidiaries shall Guarantee any
          Indebtedness or other obligation of, grant any Lien on any of its
          Property to secure any Indebtedness or other obligation of, make any
          Investment in (except as permitted under Section 8.10(e) and (f)), or
          provide any other form of credit support to, any Unrestricted
          Subsidiary, and neither the Company nor any of its Subsidiaries shall
          enter into (i) any management contract or agreement with any
          Unrestricted Subsidiary, except upon the prior written consent of
          Majority Lenders, not to be unreasonably withheld, or (ii) any other
          contract or agreement with any Unrestricted Subsidiary, except in the
          course of ordinary business on terms no less favorable to the Company
          or such Subsidiary, as applicable, than could be obtained in a
          comparable arm's length transaction from an unaffiliated party.

     (c)  No Unrestricted Subsidiary shall enter into any contract or agreement
          to acquire, or acquire any Property, except upon the prior approval of
          Majority Lenders with respect to (i) existing or potential
          environmental or litigation liabilities and (ii) satisfaction as to
          any governmental approval as required.

     (d)  In the event Unrestricted Subsidiaries shall fail to consummate an
          acquisition of Property prior to September 30, 1998 with a fair market
          value of not less than the amount of Investments made in such
          Unrestricted Subsidiaries pursuant to Section 8.10(e) and (f), then on
          and after October 1, 1998 each Unrestricted Subsidiary shall be deemed
          to be a "Subsidiary" of the Company for purposes of this Agreement and
          shall be subject to the terms and conditions hereof.

                  ARTICLE III. -- Conditions of Effectiveness

     (S) 3.1.    Effective Date.  This Amendment shall become effective as of
the date first above written when and only when Agent shall have received, at
Agent's office, a counterpart of this Amendment executed and delivered by the
Company and Majority Lenders.

                 ARTICLE IV. -- Representations and Warranties

     (S) 4.1.    Representations and Warranties of the Company.  In order to
induce Agent and Lenders to enter into this Amendment, the Company represents
and warrants to Agent and Lenders that:

          (a) The representations and warranties contained in Section 7 of the
     Original Agreement, are true and correct at and as of the time of the
     effectiveness hereof, subject to the amendment of certain of the Schedules
     to the Credit Agreement as attached hereto.

          (b) The Company and the Subsidiaries are duly authorized to execute
     and deliver this Amendment and the other Amendment Documents to the extent
     a party thereto, and the 
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     Company is and will continue to be duly authorized to borrow and perform
     its obligations under the Credit Agreement. The Company and the
     Subsidiaries have duly taken all corporate action necessary to authorize
     the execution and delivery of this Amendment and the other Amendment
     Documents, to the extent a party thereto, and to authorize the performance
     of their respective obligations thereunder.

          (c) The execution and delivery by the Company and the Subsidiaries of
     this Amendment and the other Amendment Documents, to the extent a party
     thereto, the performance by the Company and the Subsidiaries of their
     respective obligations hereunder and thereunder, and the consummation of
     the transactions contemplated hereby and thereby, do not and will not
     conflict with any provision of law, statute, rule or regulation or of the
     certificate or articles of incorporation and bylaws of the Company or any
     Subsidiary, or of any material agreement, judgment, license, order or
     permit applicable to or binding upon the Company or any Subsidiary, or
     result in the creation of any lien, charge or encumbrance upon any assets
     or properties of the Company or any Subsidiary, except in favor of Agent
     for the benefit of Lenders.  Except for those which have been duly
     obtained, no consent, approval, authorization or order of any court or
     governmental authority or third party is required in connection with the
     execution and delivery by the Company or any Subsidiary of this Amendment
     or any other Amendment Document, to the extent a party thereto, or to
     consummate the transactions contemplated hereby and thereby.

          (d) When this Amendment and the other Amendment Documents have been
     duly executed and delivered, each of the Basic Documents, as amended by
     this Amendment and the other Amendment Documents, will be a legal and
     binding instrument and agreement of the Company and the Subsidiaries, to
     the extent a party thereto, enforceable in accordance with its terms,
     (subject, as to enforcement of remedies, to applicable bankruptcy,
     insolvency and similar laws applicable to creditors' rights generally and
     to general principles of equity).

                          ARTICLE V. -- Miscellaneous

     (S) 5.1.    Ratification of Agreements.  The Original Agreement, as hereby
amended, is hereby ratified and confirmed in all respects.  The Basic Documents,
as they may be amended or affected by this Amendment and/or the other Amendment
Documents, are hereby ratified and confirmed in all respects.  Any reference to
the Credit Agreement in any Basic Document shall be deemed to refer to this
Amendment also.  The execution, delivery and effectiveness of this Amendment and
the other Amendment Documents shall not, except as expressly provided herein or
therein, operate as a waiver of any right, power or remedy of Agent or any
Lender under the Credit Agreement or any other Basic Document nor constitute a
waiver of any provision of the Credit Agreement or any other Basic Document.

     (S) 5.2.    Ratification of Security Documents.  The Company, Agent and
Lenders each acknowledge and agree that any and all indebtedness, liabilities or
obligations arising under or in connection with the Notes are Obligations and is
secured indebtedness under, and is secured by, each and every Security Document
to which the Company is a party.  The Company hereby re-pledges, 
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re-grants and re-assigns a security interest in and lien on every asset of the
Company described as collateral in any Security Document.

     (S) 5.3.    Survival of Agreements.  All representations, warranties,
covenants and agreements of the Company herein and in the other Amendment
Documents shall survive the execution and delivery of this Amendment and the
other Amendment Documents and the performance hereof and thereof, including
without limitation the making or granting of each Loan, and shall further
survive until all of the Obligations are paid in full.  All statements and
agreements contained in any certificate or instrument delivered by the Company
or any Subsidiary hereunder, under the other Amendment Documents or under the
Credit Agreement to Agent or any Lender shall be deemed to constitute
representations and warranties by, or agreements and covenants of, the Company
under this Amendment and under the Credit Agreement.

     (S) 5.4.    Basic Documents.  This Amendment and each of the other
Amendment Documents is a Basic Document, and all provisions in the Credit
Agreement pertaining to Basic Documents apply hereto and thereto.

     (S) 5.5.    GOVERNING LAW.  THIS AMENDMENT AND THE OTHER AMENDMENT
DOCUMENTS SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE
STATE OF NEW YORK AND ANY APPLICABLE LAWS OF THE UNITED STATES OF AMERICA IN ALL
RESPECTS, INCLUDING CONSTRUCTION, VALIDITY AND PERFORMANCE.

     (S) 5.6.    Counterparts.  This Amendment and each of the other Amendment
Documents may be separately executed in counterparts and by the different
parties hereto in separate counterparts, each of which when so executed shall be
deemed to constitute one and the same Amendment or Amendment Document, as the
case may be.
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     IN WITNESS WHEREOF, this Amendment is executed as of the date first above
written.

                              PLAINS RESOURCES INC.

                              By: /s/  PHILLIP D. KRAMER
                                  -----------------------------------------
                                 Phillip D. Kramer
                                 Vice President and Chief Financial Officer


                              ING (U.S.) CAPITAL CORPORATION,
                              f/k/a Internationale Nederlanden (U.S.) Capital
                              Corporation, individually as a Lender and as
                              Agent

                              By: /s/  CHRISTOPHER R. WAGNER
                                  -----------------------------------------
                                 Christopher R. Wagner, Vice President


                              BANKBOSTON, N.A., Lender

                              By: /s/  TERRENCE RONAN
                                  ----------------------------------------
                                 Name: Terrence Ronan
                                 Title:   Vice President


                              DEN NORSKE BANK ASA, Lender

                              By: /s/  BYRON L. COOLEY
                                  ----------------------------------------
                                 Name: Byron L. Cooley
                                 Title:   Senior Vice President

                              By: /s/  J. MORTEN KREUTZ
                                  ----------------------------------------
                                 Name: J. Morten Kreutz
                                 Title:   Vice President


                              WELLS FARGO BANK (TEXAS),
                              NATIONAL ASSOCIATION
                              (f/k/a First Interstate Bank of Texas, N.A.),
                              Lender

                              By: /s/  ANN M. RHOADS
                                  ----------------------------------------
                                 Ann M. Rhoads, Vice President
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                              CHASE BANK OF TEXAS, NATIONAL ASSOCIATION (f/k/a
                              Texas Commerce Bank National Association), Lender

                              By: /s/  RUSSELL M. JOHNSON
                                  ----------------------------------------
                                 Name: Russell M. Johnson
                                 Title:   Vice President


                              COMERICA BANK-TEXAS, Lender

                              By: /s/  JAMES KIMBLE
                                  ----------------------------------------
                                 Name: James Kimble
                                 Title:   Assistant Vice President
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                             CONSENT AND AGREEMENT
                             ---------------------

     Each of the undersigned Subsidiary Guarantors hereby consents to the
provisions of this Amendment and the transactions contemplated herein and hereby
(i) acknowledges and agrees that any and all indebtedness, liabilities or
obligations arising under or in connection with the Notes are Obligations and
are secured indebtedness under, and are secured by, each and every Security
Document to which it is a party, (ii) re-pledges, re-grants and re-assigns a
security interest in and lien on all of its assets described as collateral in
any Security Document, (iii) ratifies and confirms its Amended and Restated
Guaranty dated April 11, 1996 made by it for the benefit of Agent and Lenders,
and (iv) expressly acknowledges and agrees that such Subsidiary Guarantor
guarantees all indebtedness, liabilities and obligations arising under or in
connection with the Notes pursuant to the terms of such Amended and Restated
Guaranty, and agrees that its obligations and covenants thereunder are
unimpaired hereby and shall remain in full force and effect.

                         PLAINS MARKETING & TRANSPORTATION INC.
                         PLAINS RESOURCES INTERNATIONAL INC.
                         PLAINS TERMINAL & TRANSFER CORPORATION
                         PLX CRUDE LINES INC.
                         STOCKER RESOURCES, INC.
                         PLX INGLESIDE INC.
                         CALUMET FLORIDA, INC.
                         PLAINS ILLINOIS INC.


                         By: /s/  PHILLIP D. KRAMER
                            ----------------------------------------
                            Phillip D. Kramer
                            Vice President and Chief Financial Officer


                         STOCKER RESOURCES, L.P.

                         By:  Stocker Resources, Inc.,
                               its General Partner


                              By: /s/  PHILLIP D. KRAMER
                                  ----------------------------------------
                                 Phillip D. Kramer
                                 Vice President and Chief Financial Officer