<PAGE>

                                                                  EXECUTION COPY

================================================================================

                                                                     Exhibit 4.1

                           PORT ARTHUR FINANCE CORP.,
                                    as Issuer

                         PORT ARTHUR COKER COMPANY L.P.,
                          as Partnership and Guarantor

                           SABINE RIVER HOLDING CORP.,
               as General Partner of the Partnership and Guarantor

                           NECHES RIVER HOLDING CORP.,
               as Limited Partner of the Partnership and Guarantor

                                       and

                        THE PREMCOR REFINING GROUP INC.,
                                  as Guarantor

                                       TO

                                 HSBC BANK USA,
        as Capital Markets Trustee for the Capital Markets Senior Lenders

                                      and

                      DEUTSCHE BANK TRUST COMPANY AMERICAS,
                  as Collateral Trustee for the Secured Parties
                                  ____________


                          First Supplemental Indenture

                            Dated as of June 6, 2002

                                  ____________


                      12.50% Senior Secured Notes Due 2009



================================================================================

<PAGE>

          FIRST SUPPLEMENTAL INDENTURE, dated as of June 6, 2002, (this
"Supplemental Indenture"), to the Indenture, dated as of August 19, 1999 (the
"Indenture"), among PORT ARTHUR FINANCE CORP., a corporation duly organized and
existing under the laws of the State of Delaware (herein called the "Issuer"),
having its principal office at Port Arthur, Texas, PORT ARTHUR COKER COMPANY
L.P., a limited partnership duly organized and existing under the laws of the
State of Delaware (herein called the "Partnership"), having its principal office
at Port Arthur, Texas, SABINE RIVER HOLDING CORP., a corporation duly organized
and existing under the laws of the State of Delaware (herein called the "General
Partner"), having its principal office at Port Arthur, Texas, NECHES RIVER
HOLDING CORP., a corporation duly organized and existing under the laws of the
State of Delaware (herein called the "Limited Partner", and together with the
General Partner, the "Original Guarantors"), having its principal office at Port
Arthur, Texas, THE PREMCOR REFINING GROUP INC., a corporation duly organized and
existing under the laws of the State of Delaware (herein called "PRG" and,
together with the Original Guarantors, the "Guarantors"), having its principal
office in St. Louis, Missouri, HSBC BANK USA, a New York banking corporation and
trust company, as Capital Markets Trustee for the Capital Markets Senior Lenders
(herein called the "Capital Markets Trustee"), and DEUTSCHE BANK TRUST COMPANY
AMERICAS (formerly known as "Bankers Trust Company"), a New York banking
corporation and trust company, as Collateral Trustee for the Secured Parties
(herein called the "Collateral Trustee").


                                    RECITALS

          WHEREAS, Section 902 of the Indenture provides that, with the consent
of Majority Bondholders, the Issuer, the Original Guarantors and the Capital
Markets Trustee may enter into an indenture or indentures supplemental thereto
for the purpose of adding any provisions to or changing in any manner or
eliminating any of the provisions of the Indenture or the other Financing
Documents;

          WHEREAS, in connection with a restructuring of the Senior Debt, the
Borrower, the Partnership and the Original Guarantors have proposed (i) to amend
and to restate the Common Security Agreement in order to eliminate or modify
certain covenants and agreements contained therein, to release certain security
interests created thereby and to make other changes related or incidental to the
foregoing and (ii) to amend the Indenture to provide for related changes;

          WHEREAS, such restructuring entails, among other things, the
following: (i) prepayment of all outstanding Senior Debt other than the
Securities and the cancellation of all Senior Debt Commitments; (ii) elimination
of provisions related to the governance, ultimate ownership and certain
transactions of the Partnership, the Issuer, the General Partner and the Limited
Partner; (iii) contribution of the General Partner to PRG, resulting in the
General Partner's becoming a wholly-owned subsidiary of PRG and a member of the
Premcor consolidated group; (iv) addition of an unsecured, unconditional
guarantee by PRG of all principal of and interest on the Securities; (v)
elimination of the account waterfall and all secured accounts other than the
Principal & Interest Accrual Account, the Debt Service Reserve Account and
certain other accounts and the modification of those remaining accounts; (vi)
modification of covenants to permit establishment of a new

                                      -2-

<PAGE>

Partnership/PRG working capital facility; (vii) elimination of security
interests in crude oil, intermediate products and refined products, and all
Accounts other than the Principal & Interest Accrual Account, the Debt Service
Reserve Account and certain other accounts; (viii) creation of an exception to
the restriction on security interests to permit the grant of a security interest
in the Partnership's crude oil, intermediate products and refined products to
the lenders under any Partnership/PRG working capital facility; and (ix)
modification of the Restricted Payments provisions; and

          WHEREAS, Majority Bondholders have consented to the execution and
delivery of an amended and restated Common Security Agreement, an amendment to
the Transfer Restrictions Agreement and of this Supplemental Indenture to give
effect to the foregoing and other agreed amendments.

          NOW THEREFORE, in consideration of the premises and the mutual
covenants contained herein, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereby
agree as follows:


                                   ARTICLE ONE

                            DEFINITIONS IN INDENTURE

          Capitalized terms used and not otherwise defined in this Supplemental
Indenture and in any certificate or other document executed by any party in
connection herewith shall have the meanings assigned to them in the Indenture.


                                   ARTICLE TWO

                                   AMENDMENTS

          To give effect to the amendments described in the recitals, the
following amendments are hereby made to the Indenture.

SECTION 201.   The Indenture is hereby amended by replacing all references to
"Bankers Trust Company" with references to "Deutsche Bank Trust Company
Americas."

SECTION 202.   The recitals to the Indenture are hereby amended by: (a)
deleting the words "or Private Exchange Securities" in the fourth line of the
first paragraph thereof; (b) replacing the comma after the word "Securities" in
the fourth line of the first paragraph with the word "or"; (c) deleting the
words "and the Private Exchange Securities" in the fifth line of the first
paragraph thereof; and (d) replacing the comma after the word "Securities" in
the fifth line of the first paragraph with the word "and".

SECTION 203.   Section 101 of the Indenture is hereby amended by:

       (a)  replacing the reference to "Clark Refining Holdings Inc." in the
definition of

                                       -3-

<PAGE>

     "Purchase Agreement" with a reference to "Premcor Inc.";

          (b) replacing the definition of "Common Security Agreement" with the
     words "means the Amended and Restated Common Security Agreement, dated as
     of June 6, 2002, among Port Arthur Finance Corp., Port Arthur Coker Company
     L.P., Sabine River Holding Corp., Neches River Holding Corp., Deutsche Bank
     Trust Company Americas, as Collateral Trustee for the Senior Lenders, HSBC
     Bank USA, as Capital Markets Trustee for the Capital Markets Senior
     Lenders, and Deutsche Bank Trust Company Americas, as Depositary Bank, as
     the same may be amended or supplemented in accordance with its terms and in
     effect from time to time.";

          (c) deleting the words "clause (a) and (c) of" after the words
     "pursuant to" in the definition of "Redemption Price";

          (d) replacing the definition of "Exchange Offer" with the words "has
     the meaning specified in the definition of the term "Registered Exchange
     Offer" in the Registration Rights Agreement.";

          (e) inserting the following definition in the appropriate alphabetical
     order:

              "PRG" means Premcor Refining Company Inc.;

          (f) replacing the definition of "Exchange Securities" with the words
     "has the meaning specified in the Registration Rights Agreement.";

          (g) replacing the definition of "Original Securities" with the words
     "has the meaning specified in the definition of the term "Initial
     Securities" in the Registration Rights Agreement.";

          (h) deleting the definition of "Private Exchange Securities";

          (i) replacing the definition of "Registration Rights Agreement" with
     the words "means the Registration Rights Agreement, dated as of June
     6, 2002, among the Issuer, the Partnership, the General Partner, the
     Limited Partner, PRG and the Capital Markets Trustee.";

          (j) replacing the definition of "Restricted Securities" with the
     following words: "has the meaning specified in the Registration Rights
     Agreement.";

          (k) deleting the words "and the Private Exchange Securities" in the
     second line of the definition of "Securities"; and

          (1) replacing the comma after the word "Securities" in the second line
     of the definition of "Securities" with the word "and".

SECTION 204.    Section 202 of the Indenture is hereby amended by inserting the
following paragraph after the first paragraph thereof:

"[Include if Security is a Restricted Global Security as a result of the
Guarantee by PRG not being registered under the Securities Act -- THE GUARANTEE
OF THE PREMCOR REFINING

                                       -4-

<PAGE>

GROUP INC. ACCOMPANYING THIS SECURITY (THE "PRG GUARANTEE") HAS NOT BEEN
REGISTERED UNDER THE U.S. SECURITIES ACT OF 1933 (THE "SECURITIES ACT"), AND AS
A RESULT, THIS SECURITY MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE
TRANSFERRED EXCEPT (A)(l) TO A PERSON WHO THE TRANSFEROR REASONABLY BELIEVES IS
A QUALIFIED INSTITUTIONAL BUYER (WITHIN THE MEANING OF RULE 144A UNDER THE
SECURITIES ACT) ACQUIRING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF ONE OR MORE
QUALIFIED INSTITUTIONAL BUYERS IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE
144A, (2) IN AN OFFSHORE TRANSACTION COMPLYING WITH THE REQUIREMENTS OF RULE 903
OR 904 OF REGULATION S UNDER THE SECURITIES ACT, (3) PURSUANT TO AN EXEMPTION
FROM REGISTRATION UNDER THE SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER (IF
AVAILABLE) OR (4) PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
SECURITIES ACT AND (B) IN ACCORDANCE WITH ALL APPLICABLE SECURITIES LAWS OF THE
STATES OF THE UNITED STATES AND OTHER JURISDICTIONS. THE TRANSFEROR IS REQUIRED
TO DELIVER WRITTEN CONFIRMATION TO THE CAPITAL MARKETS TRUSTEE THAT THE TRANSFER
IS BEING MADE IN COMPLIANCE WITH THE PARTICULAR RESTRICTIONS ON TRANSFER
SPECIFIED IN CLAUSE (A)(2), (A)(3), OR (A)(4) ABOVE. THE HOLDER HEREOF, BY
ACCEPTING THE PRG GUARANTEE, REPRESENTS AND AGREES FOR THE BENEFIT OF THE ISSUER
AND THE GUARANTORS THAT IT WILL NOTIFY ANY PURCHASER OF THIS SECURITY FROM IT OF
THE RESALE RESTRICTIONS REFERRED TO ABOVE. NO REPRESENTATION HAS BEEN OR CAN BE
MADE AS TO THE AVAILABILITY OF THE EXEMPTION PROVIDED BY RULE 144 FOR RESALES OF
THIS SECURITY.]"

SECTION 205. Section 203 of the Indenture is hereby amended by: (a) replacing
the words "and, together with the Partnership and the General Partner, the
"Guarantors")" with the words ", The Premcor Refining Group Inc. (herein called
"PRG" and together with the Partnership, the General Partner and the Limited
Partner, the "Guarantors")" following the words "(herein called the "Limited
Partner" in the sixth line of the first paragraph thereof; (b) deleting the
words "clauses (a) and (c) of" after the word "under" in the second line of the
second paragraph thereof; (c) delete the words "of this clause (1)" after the
words "subclause (C)" in the third line of clause (D) of the fourth paragraph
thereof; (d) replacing the words "neither the Issuer nor any of the Guarantors
is" with the words "PRG is not" in the second line of the 14th paragraph
thereof; (e) deleting the words "(including Bank Senior Debt)" in the 13th line
of the 15th paragraph thereof; (f) replacing the reference to "August 19, 1999"
with a reference to "June 6, 2002" in the second line of the 16th paragraph
thereof; (g) adding the words "by the Partnership, the General Partner and the
Limited Partner" after the words "the Guarantee" in the seventh line of the 24th
paragraph thereof; (h) adding the sentence "The Guarantee by PRG is unsecured."
after the second sentence of the 24th paragraph thereof; (i) deleting the words
"as set forth in Sections 5.05 and 10.12 of the Common Security Agreement and
other than" in the eighth line of the 24th paragraph thereof; (j) deleting the
words "and any Oil Payment Reimbursement Obligations incurred pursuant to the
Oil Payment Reimbursement Agreement," in the 12th line of the 24th paragraph and
in the 15th line of the 24th paragraph thereof; and (k) deleting the words "in
each case" in the 16th line of the 24th paragraph thereof.

                                       -5-

<PAGE>

SECTION 206. Section 205 of the Indenture is hereby amended by: (a) deleting the
words "as set forth in Sections 5.05 and 10.12 of the Common Security Agreement
and other than" in the second line of the fourth paragraph thereof; (b) adding
the words "by the Partnership, the General Partner and the Limited Partner"
after the words "the Guarantee" in the fourth line of the fourth paragraph
thereof; (c) deleting the words "and any Oil Payment Reimbursement Obligations
incurred pursuant to the Oil Payment Reimbursement Agreement," in the sixth line
of the fourth paragraph thereof; (d) deleting the words "in each case" in the
seventh line of the fourth paragraph thereof; and (e) adding a signature line
for "The Premcor Refining Group Inc." at the end of Section 205 thereof.

SECTION 207. Section 311 of the Indenture is hereby amended by: (a) adding the
words "by the Partnership, the General Partner and the Limited Partner" after
the words "The Guarantee" in the seventh line thereof; (b) deleting the words
"as set forth in Sections 5.05 and 10.12 of the Common Security Agreement and
other than" in the eighth line thereof; (c) deleting the words "and any Oil
Payment Reimbursement Obligations incurred pursuant to the Oil Payment
Reimbursement Agreement," in the 12th line thereof; (d) adding the words "by the
Partnership, the General Partner and the Limited Partner" after the words "the
Guarantee" in the 13th line thereof; (e) deleting the words "and any Oil Payment
Reimbursement Obligations incurred pursuant to the Oil Payment Reimbursement
Agreement," in the 15th line thereof; and (f) deleting the words "in each case"
in the 16th line thereof.

SECTION 208. Section 704 of the Indenture is hereby amended by replacing the
words "the Issuer and the Guarantors" with the words "PRG, on behalf of the
Issuer and the other Guarantors," in the first line thereof.

SECTION 209. Section 705 of the Indenture is hereby amended by replacing the
words "the Issuer and the Guarantors" with the words "PRG, on behalf of the
Issuer and the other Guarantors," in the third and eighth line thereof.

SECTION 210. Section 802 of the Indenture is hereby amended by: (a) replacing
the number "15" with the number "2" in the 11th line of the first paragraph
thereof; (b) adding the word "after" after the words "Business Days" in the 12th
line of the first paragraph thereof; and (c) deleting the words "(including Bank
Senior Lenders)" in the sixth line of the second paragraph thereof.

SECTION 211. Section 902 of the Indenture is hereby amended by replacing the
reference to Section 4.01(u) of the Common Security Agreement in the seventh
line of the second paragraph thereof with reference to Section 4.01 (r) of the
Common Security Agreement.

SECTION 212. Section 1001 of the Indenture is hereby amended in its entirety to
read as follows: "The Issuer and the Guarantors covenant and agree for the
benefit of the Holders of Security Outstanding, that so long as any Securities
is Outstanding, each of them shall duly perform, observe and comply with all of
its obligations, covenants and agreements set forth in the Common Security
Agreement, including without limitation (a) with respect to the Partnership and
the Issuer, the covenants set forth in Section 4.01 of the Common Security
Agreement, (b) with respect to the Partners, the covenants set forth in Section
4.02 of the Common Security Agreement and (c) with respect to PRG, the covenants
set forth in Section 4.03 of the Common Security Agreement; all such
obligations, covenants and agreements, together with any schedules, appendices,
defined terms

                                       -6-

<PAGE>

related thereto, are hereby incorporated by reference mutatis mutandis for the
benefit of the Holders of Securities. It is understood and agreed that PRG is
not subject to any covenants or agreements set forth in, and has no other
obligations under, the Common Security Agreement other than in respect of the
Guarantee in Section 12.01 thereof and the covenants set forth in Sections 4.03
and 4.04 thereof."

SECTION 213.  Section 1006 of the Indenture is hereby amended by: (a) replacing
the words "The Issuer or the Guarantors" with the words "PRG, on behalf of the
Issuer and the other Guarantors," in the first line thereof; and (b) replacing
each reference to "the Issuer and the Guarantors" in such Section with the words
"PRG, on behalf of the Issuer and the other Guarantors.

SECTION 214.  Section 1007 of the Indenture is hereby amended by replacing the
words "the Issuer and the Guarantors" with the words "PRG, on behalf of the
Issuer and the other Guarantors," in the second and fifth lines thereof.

SECTION 215.  Section 1008 of the Indenture is hereby amended by replacing the
reference to Section 401(u) of the Common Security Agreement in the 12th line
of the first paragraph thereof with reference to Section 401(r) of the Common
Security Agreement.

SECTION 216.  Section 1303 of the Indenture is hereby amended by: (a) replacing
the words "the Issuer" with the words "each of the Issuer and each Guarantor" in
the second line thereof; (b) replacing the word "obligation" with the word
"obligations" in the fourth line thereof; (c) adding the words ", any covenants
and obligations under the other Financing Documents" after the words "Common
Security Agreement" in fifth line thereof; (d) replacing the reference to
"Section 901(2), 901(7), and 1002 through 1007 inclusive" in the sixth line
thereof with a reference to "Section 901(2), 90l(7), 1001 and 1003 through
1007 inclusive"; (e) adding the words "or Section 5.01(b) or 5.01(c) hereof"
after the words "Common Security Agreement" in the eighth line thereof; and (f)
deleting the words "(to the extent so specified in the case of Section 10.01 of
the Common Security Agreement)" in the 14th line thereof.

SECTION 217.  The Corporate Trust Office for the purpose of Section 105 of the
Indenture shall be as follows: "HSBC Bank USA, Issuer Services, 452 Fifth
Avenue, New York, New York 10018-2706 or to such other address of which the
Capital Markets Trustee has given notice".


                                  ARTICLE THREE

                                    GUARANTEE

 SECTION 301. PRG as a Party and Guarantor.

         PRG acknowledges that, as a result of the execution of this
Supplemental Indenture, it is a party and a Guarantor for all purposes of the
Indenture including without limitation of Section 117 thereof, and agrees to be
bound by the Indenture and to perform in accordance with its terms all the
obligations which by the terms of the Indenture and the Securities are required
to be performed by a Guarantor thereunder.

                                       -7-

<PAGE>

 SECTION 302.       Guarantee of PRG.

             Without limiting the generality of Section 301 hereof, PRG (a)
agrees with each Holder of a Security authenticated and delivered by the Capital
Markets Trustee and with the Capital Markets Trustee on behalf of such Holder to
be unconditionally and jointly and severally bound by the terms and provisions
of the Guarantee set forth in Section 205 of the Indenture and (b) authorizes
the Issuer, in the name and on behalf of PRG, to confirm such Guarantee to the
Holder of each such Security by its execution and delivery of each such
Security, with such Guarantee endorsed thereon, authenticated and delivered by
the Capital Markets Trustee.

 SECTION 303.       Execution and Delivery of Guarantee.

             To evidence the Guarantee set forth in Section 302 hereof, PRG
agrees that a notation of the Guarantee substantially in the form set forth in
Section 205 of the Indenture shall be endorsed on each Security authenticated
and delivered by the Capital Markets Trustee and that this Supplemental
Indenture shall be executed on behalf of the Guarantors by a Responsible Officer
of each.

             PRG agrees that the Guarantee set forth in Article Twelve of the
Indenture will remain in full force and effect and apply to all the Securities
notwithstanding any failure to endorse on each Security a notation of the
Guarantee.

 SECTION 304.       Delivery of Security.

             Concurrently with the execution and delivery of this Supplemental
Indenture, the Issuer shall deliver a Security that bears the legends required
to be set forth on the face of a Restricted Security pursuant to Section 202 of
the Indenture, in an aggregate principal amount of $255,000,000, executed by the
Issuer, and having endorsed thereon the Guarantee by the Guarantors, to the
Capital Markets Trustee for authentication, together with an Issuer Order for
the authentication and delivery of such Security and Officers' Certificates, all
in accordance with Section 303 of the Indenture. The Capital Markets Trustee in
accordance with such Issuer Order shall authenticate and deliver such Security,
in accordance with Section 303 of the Indenture, in exchange for a like
principal amount of Original Securities surrendered for cancellation in
accordance with Section 309 of the Indenture. The new Security so issued,
authenticated and delivered shall be a Restricted Security for all purposes of
the Indenture.


                                  ARTICLE FOUR

                                  MISCELLANEOUS

 SECTION 401.       Effectiveness,

             This Supplemental Indenture shall come into full force and effect
in accordance with Section 5.03 of the Master Amendment Agreement, dated as of
the date hereof, among the Issuer, the Partnership, General Partner, the Limited
Partner, PRG, Premcor USA Inc., Premcor Inc., Deutsche

                                       -8-

<PAGE>

Bank Trust Company Americas, as Collateral Trustee for the Senior Lenders, and
HSBC Bank USA, as Capital Markets Trustee for the Capital Markets Senior
Lenders. Upon effectiveness, the Indenture shall be supplemented in accordance
herewith, and this Supplemental Indenture shall form a part of the Indenture for
all purposes, and every Holder of Securities heretofore or hereafter
authenticated and delivered under the Indenture shall be bound thereby, provided
that the Guarantee of PRG pursuant to Section 1201 of the Indenture as amended
hereby shall only become effective upon completion of the transactions
contemplated by Section 5.02 of the Master Amendment Agreement.

SECTION 402.    Indenture Remains in Full Force and Effect.

            Except as supplemented hereby, the Indenture shall remain in full
force and effect.

SECTION 403.    Indenture and Supplemental Indenture Construed Together.

            This Supplemental Indenture is an indenture supplemental to and in
implementation of the Indenture and the Indenture and this Supplemental
Indenture shall henceforth be read and construed together.

SECTION 404.    Confirmation and Preservation of Indenture.

            The Indenture as supplemented by this Supplemental Indenture is in
all respects confirmed and preserved.

SECTION 405.    Conflict with Trust Indenture Act.

            If any provision hereof limits, qualifies, or conflicts with, a
provision of the Trust Indenture Act that is required under such Act to be a
part of and govern this Supplemental Indenture, the latter provision shall
control.

SECTION 406.    Effect of Headings.

            The Article and Section headings herein are for convenience of
reference only and shall not affect the construction hereof.

SECTION 407.    Separability Clause.

            If any provision in this Supplemental Indenture shall be invalid,
illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

SECTION 408.    Benefits of Supplemental Indenture.

            Nothing in this Supplemental Indenture or in the Securities, express
or implied, shall give to any Person, other than the parties hereto
and their successors hereunder and the Bondholders, any benefit or any legal or
equitable right, remedy or claim under this Supplemental Indenture.

                                       -9-

<PAGE>

SECTION 409.    Governing Law.

            This Supplemental Indenture shall be governed by and construed in
accordance with the laws of the State of New York.

SECTION 410.    Interpretation.

            This Supplemental Indenture shall be construed and interpreted to
give effect to the intentions of the parties set forth in the recitals and the
Amended and Restated Common Security Agreement.

SECTION 411.    Counterparts.

            This Supplemental Indenture may be executed in any number of
counterparts, each of which when so executed shall be deemed to be an original
but all such counterparts together constitute but one in the same instrument.

SECTION 412.    Successors.

            All agreements of the Issuer and the Guarantors in this Supplemental
Indenture shall bind its successors. All agreements of the Capital Markets
Trustee and the Collateral Trustee in this Supplemental Indenture shall bind its
successors.

SECTION 413.    Capital Markets Trustee Not Responsible for Recitals.

            The recitals herein contained are made by the Issuer and the
Guarantors and not by the Capital Markets Trustee or the Collateral Trustee, and
neither the Capital Markets Trustee nor the Collateral Trustee assume
responsibility for the correctness thereof. Neither Capital Markets Trustee nor
the Collateral Trustee shall be responsible in any manner whatsoever for or in
respect of the validity or sufficiency of this Supplemental Indenture.

                                       -10-

<PAGE>

            IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed, and their respective corporate or partnership
seals to be hereunto affixed and attested, all as of the day and year first
above written.


                                          PORT ARTHUR FINANCE CORP.


                                          By: ________________________________
                                              Name:
                                              Title:

                                          PORT ARTHUR COKER COMPANY L.P.
                                          By: SABINE RIVER HOLDING CORP.,
                                              as General Partner


                                          By: ________________________________
                                              Name:
                                              Title:

                                          SABINE RIVER HOLDING CORP.


                                          By: ________________________________
                                              Name:
                                              Title:

                                          NECHES RIVER HOLDING CORP.


                                          By: ________________________________
                                              Name:
                                              Title:

                                          THE PREMCOR REFINING GROUP INC.


                                          By: ________________________________
                                              Name:
                                              Title:

                                      -11-

<PAGE>

                                        HSBC BANK USA,
                                        as Capital Markets Trustee for the
                                        Capital Markets Senior Lenders


                                        By: __________________________________
                                            Name:
                                            Title:

                                        By: __________________________________
                                            Name:
                                            Title:




                                        DEUTSCHE BANK TRUST COMPANY AMERICAS,
                                        as Collateral Trustee for the Secured
                                        Parties


                                        By: __________________________________
                                            Name:
                                            Title:

                                        By: __________________________________
                                            Name:
                                            Title:

                                      -12-