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                                  Exhibit 4.03

                           CERTIFICATE OF DESIGNATIONS

                                       OF

                 JUNIOR PARTICIPATING PREFERRED STOCK, SERIES I

                                       OF

                      VALERO REFINING AND MARKETING COMPANY

                         (PURSUANT TO SECTION 151 OF THE
                        DELAWARE GENERAL CORPORATION LAW)

                        --------------------------------

                  Valero Refining and Marketing Company, a corporation organized
and existing under the General Corporation Law of the State of Delaware
(hereinafter called the "corporation"), hereby certifies that the following
resolution was adopted by the Board of Directors of the corporation as required
by Section 151 of the General Corporation Law at a meeting duly called and held
on July 17, 1997:

                  RESOLVED, that pursuant to the authority granted to and vested
in the Board of Directors of this corporation (hereinafter called the "Board of
Directors" or the "Board") in accordance with the provisions of the Restated
Certificate of Incorporation, the Board of Directors hereby creates a series of
Preferred Stock, par value $0.01 per share (the "Preferred Stock"), of the
corporation and hereby states the designation and number of shares, and fixes
the relative rights, preferences, and limitations thereof as follows:

                  Junior Participating Preferred Stock, Series I:

                  Section 1. Designation and Amount. The shares of such series
shall be designated as "Junior Participating Preferred Stock, Series I" (the
"Series I Preferred Stock") and the number of shares constituting the Series I
Preferred Stock shall be 1,500,000. Such number of shares may be increased or
decreased by resolution of the Board of Directors; provided, that no decrease
shall reduce the number of shares of Series I Preferred Stock to a number less
than the number of shares then outstanding plus the number of shares reserved
for issuance upon the exercise of outstanding options, rights or warrants or
upon the conversion of any outstanding securities issued by the corporation
convertible into Series I Preferred Stock.

                  Section 2. Dividends and Distributions.

                  (A) Subject to the rights of the holders of any shares of any
         series of Preferred Stock (or any similar stock) ranking prior and
         superior to the Series I Preferred Stock with


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         respect to dividends, the holders of shares of Series I Preferred
         Stock, in preference to the holders of Common Stock, par value $0.01
         per share (the "Common Stock"), of the corporation, and of any other
         junior stock, shall be entitled to receive, when, as and if declared by
         the Board of Directors out of funds legally available for the purpose,
         quarterly dividends payable in cash on the first day of March, June,
         September and December in each year (each such date being referred to
         herein as a "Quarterly Dividend Payment Date"), commencing on the first
         Quarterly Dividend Payment Date after the first issuance of a share or
         fraction of a share of Series I Preferred Stock, in an amount per share
         (rounded to the nearest cent) equal to the greater of (a) $1 or (b)
         subject to the provision for adjustment hereinafter set forth, 100
         times the aggregate per share amount of all cash dividends, and 100
         times the aggregate per share amount (payable in kind) of all non-cash
         dividends or other distributions, other than a dividend payable in
         shares of Common Stock or a subdivision of the outstanding shares of
         Common Stock (by reclassification or otherwise), declared on the Common
         Stock since the immediately preceding Quarterly Dividend Payment Date
         or, with respect to the first Quarterly Dividend Payment Date, since
         the first issuance of any share or fraction of a share of Series I
         Preferred Stock. In the event the corporation shall at any time declare
         or pay any dividend on the Common Stock payable in shares of Common
         Stock, or effect a subdivision or combination or consolidation of the
         outstanding shares of Common Stock (by reclassification or otherwise
         than by payment of a dividend in shares of Common Stock) into a greater
         or lesser number of shares of Common Stock, then in each such case the
         amount to which holders of shares of Series I Preferred Stock were
         entitled immediately prior to such event under clause (b) of the
         preceding sentence shall be adjusted by multiplying such amount by a
         fraction, the numerator of which is the number of shares of Common
         Stock outstanding immediately after such event and the denominator of
         which is the number of shares of Common Stock that were outstanding
         immediately prior to such event.

                  (B) The corporation shall declare a dividend or distribution
         on the Series I Preferred Stock as provided in paragraph (A) of this
         Section immediately after it declares a dividend or distribution on the
         Common Stock (other than a dividend payable in shares of Common Stock);
         provided that, in the event no dividend or distribution shall have been
         declared on the Common Stock during the period between any Quarterly
         Dividend Payment Date and the next subsequent Quarterly Dividend
         Payment Date, a dividend of $1 per share on the Series I Preferred
         Stock shall nevertheless be payable on such subsequent Quarterly
         Dividend Payment Date.

                  (C) Dividends shall begin to accrue and be cumulative on
         outstanding shares of Series I Preferred Stock from the Quarterly
         Dividend Payment Date next preceding the date of issue of such shares,
         unless the date of issue of such shares is prior to the record date for
         the first Quarterly Dividend Payment Date, in which case dividends on
         such shares shall begin to accrue from the date of issue of such
         shares, or unless the date of issue is a Quarterly Dividend Payment
         Date or is a date after the record date for the determination of
         holders of shares of Series I Preferred Stock entitled to receive a
         quarterly dividend and before such Quarterly Dividend Payment Date, in
         either of which events such dividends shall begin to accrue and be
         cumulative from such Quarterly Dividend Payment Date. Accrued but
         unpaid dividends shall not bear interest. Dividends paid on the shares
         of Series I Preferred Stock in

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         an amount less than the total amount of such dividends at the time
         accrued and payable on such shares shall be allocated pro rata on a
         share-by-share basis among all such shares at the time outstanding. The
         Board of Directors may fix a record date for the determination of
         holders of shares of Series I Preferred Stock entitled to receive
         payment of a dividend or distribution declared thereon, which record
         date shall be not more than 60 days prior to the date fixed for the
         payment thereof.

                  Section 3. Voting Rights. The holders of shares of Series I
Preferred Stock shall have the following voting rights:

                  (A) Subject to the provision for adjustment hereinafter set
         forth, each share of Series I Preferred Stock shall entitle the holder
         thereof to 100 votes on all matters submitted to a vote of the
         stockholders of the corporation. In the event the corporation shall at
         any time declare or pay any dividend on the Common Stock payable in
         shares of Common Stock, or effect a subdivision or combination or
         consolidation of the outstanding shares of Common Stock (by
         reclassification or otherwise than by payment of a dividend in shares
         of Common Stock) into a greater or lesser number of shares of Common
         Stock, then in each such case the number of votes per share to which
         holders of shares of Series I Preferred Stock were entitled immediately
         prior to such event shall be adjusted by multiplying such number by a
         fraction, the numerator of which is the number of shares of Common
         Stock outstanding immediately after such event and the denominator of
         which is the number of shares of Common Stock that were outstanding
         immediately prior to such event.

                  (B) Except as otherwise provided herein, in any other
         Certificate of Designations creating a series of Preferred Stock or any
         similar stock, or by law, the holders of shares of Series I Preferred
         Stock and the holders of shares of Common Stock and any other capital
         stock of the corporation having general voting rights shall vote
         together as one class on all matters submitted to a vote of
         stockholders of the corporation.

                  (C) Except as set forth herein, or as otherwise provided by
         law, holders of Series I Preferred Stock shall have no special voting
         rights and their consent shall not be required (except to the extent
         they are entitled to vote with holders of Common Stock as set forth
         herein) for taking any corporate action.

                  Section 4. Certain Restrictions.

                  (A) Whenever quarterly dividends or other dividends or
         distributions payable on the Series I Preferred Stock as provided in
         Section 2 are in arrears, thereafter and until all accrued and unpaid
         dividends and distributions, whether or not declared, on shares of
         Series I Preferred Stock outstanding shall have been paid in full, the
         corporation shall not:

                           (i) declare or pay dividends, or make any other
                  distributions, on any shares of stock ranking junior (either
                  as to dividends or upon liquidation, dissolution or winding
                  up) to the Series I Preferred Stock;


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                           (ii) declare or pay dividends, or make any other
                  distributions, on any shares of stock ranking on a parity
                  (either as to dividends or upon liquidation, dissolution or
                  winding up) with the Series I Preferred Stock, except
                  dividends paid ratably on the Series I Preferred Stock and all
                  such parity stock on which dividends are payable or in arrears
                  in proportion to the total amounts to which the holders of all
                  such shares are then entitled;

                           (iii) redeem or purchase or otherwise acquire for
                  consideration shares of any stock ranking junior (either as to
                  dividends or upon liquidation, dissolution or winding up) to
                  the Series I Preferred Stock, provided that the corporation
                  may at any time redeem, purchase or otherwise acquire shares
                  of any such junior stock in exchange for shares of any stock
                  of the corporation ranking junior (either as to dividends or
                  upon dissolution, liquidation or winding up) to the Series I
                  Preferred Stock; or

                           (iv) redeem or purchase or otherwise acquire for
                  consideration any shares of Series I Preferred Stock, or any
                  shares of stock ranking on a parity with the Series I
                  Preferred Stock, except in accordance with a purchase offer
                  made in writing or by publication (as determined by the Board
                  of Directors) to all holders of such shares upon such terms as
                  the Board of Directors, after consideration of the respective
                  annual dividend rates and other relative rights and
                  preferences of the respective series and classes, shall
                  determine in good faith will result in fair and equitable
                  treatment among the respective series or classes.

                  (B) The corporation shall not permit any subsidiary of the
         corporation to purchase or otherwise acquire for consideration any
         shares of stock of the corporation unless the corporation could, under
         paragraph (A) of this Section 4, purchase or otherwise acquire such
         shares at such time and in such manner.

                  Section 5. Reacquired Shares. Any shares of Series I Preferred
Stock purchased or otherwise acquired by the corporation in any manner
whatsoever shall be retired and cancelled promptly after the acquisition
thereof. All such shares shall upon their cancellation become authorized but
unissued shares of Preferred Stock and may be reissued as part of a new series
of Preferred Stock subject to the conditions and restrictions on issuance set
forth herein, in the Restated Certificate of Incorporation, or in any other
Certificate of Designations creating a series of Preferred Stock or any similar
stock or as otherwise required by law.

                  Section 6. Liquidation, Dissolution or Winding Up. Upon any
liquidation, dissolution or winding up of the corporation, no distribution shall
be made (1) to the holders of shares of stock ranking junior (either as to
dividends or upon liquidation, dissolution or winding up) to the Series I
Preferred Stock unless, prior thereto, the holders of shares of Series I
Preferred Stock shall have received $100 per share, plus an amount equal to
accrued and unpaid dividends and distributions thereon, whether or not declared,
to the date of such payment, provided that the holders of shares of Series I
Preferred Stock shall be entitled to receive an aggregate amount per share,
subject to the provision for adjustment hereinafter set forth, equal to 100
times the aggregate amount


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to be distributed per share to holders of shares of Common Stock, or (2) to the
holders of shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Series I Preferred Stock,
except distributions made ratably on the Series I Preferred Stock and all such
parity stock in proportion to the total amounts to which the holders of all such
shares are entitled upon such liquidation, dissolution or winding up. In the
event the corporation shall at any time declare or pay any dividend on the
Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the aggregate amount to which holders of shares of Series I Preferred
Stock were entitled immediately prior to such event under the proviso in clause
(1) of the preceding sentence shall be adjusted by multiplying such amount by a
fraction the numerator of which is the number of shares of Common Stock
outstanding immediately after such event and the denominator of which is the
number of shares of Common Stock that were outstanding immediately prior to such
event.

                  Section 7. Consolidation, Merger, etc. In case the corporation
shall enter into any consolidation, merger, combination or other transaction in
which the shares of Common Stock are exchanged for or changed into other stock
or securities, cash and/or any other property, then in any such case each share
of Series I Preferred Stock shall at the same time be similarly exchanged or
changed into an amount per share, subject to the provision for adjustment
hereinafter set forth, equal to 100 times the aggregate amount of stock,
securities, cash and/or any other property (payable in kind), as the case may
be, into which or for which each share of Common Stock is changed or exchanged.
In the event the corporation shall at any time declare or pay any dividend on
the Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the amount set forth in the preceding sentence with respect to the
exchange or change of shares of Series I Preferred Stock shall be adjusted by
multiplying such amount by a fraction, the numerator of which is the number of
shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

                  Section 8. No Redemption. The shares of Series I Preferred
Stock shall not be redeemable.

                  Section 9. Rank. The Series I Preferred Stock shall rank, with
respect to the payment of dividends and the distribution of assets, junior to
all series of any other class of the corporation's Preferred Stock.

                  Section 10. Amendment. The Restated Certificate of
Incorporation of the corporation shall not be amended in any manner which would
materially alter or change the powers, preferences or special rights of the
Series I Preferred Stock so as to affect them adversely without the affirmative
vote of the holders of at least two-thirds of the outstanding shares of Series I
Preferred Stock, voting together as a single class.

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                  IN WITNESS WHEREOF, this Certificate of Designations is
executed on behalf of the corporation by its President and attested by its
Secretary this 31ST day of JULY, 1997.



                                            /s/ Edward C. Benninger
                                            -----------------------
                                            EDWARD C. BENNINGER, PRESIDENT

Attest:

/s/ Jay D. Browning
-------------------
JAY D. BROWNING, SECRETARY