AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON SEPTEMBER 1, 2005

                                           Registration Statement No. 333-125082
--------------------------------------------------------------------------------

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                              ------------------

                        POST-EFFECTIVE AMENDMENT NO. 1 ON
                                    FORM S-8
                                       TO
                                    FORM S-4
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

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

                           VALERO ENERGY CORPORATION
            (Exact name of registrant as specified in its charter)

             DELAWARE                                74-1828067
     (State or jurisdiction of                    (I.R.S. Employer
  incorporation or organization)                 Identification No.)



                                 ONE VALERO WAY
                            SAN ANTONIO, TEXAS 78249
                                (210) 345-2000
                   (Address of principal executive offices)

                   PREMCOR 2002 SPECIAL STOCK INCENTIVE PLAN
                       PREMCOR 2002 EQUITY INCENTIVE PLAN
                        PREMCOR 1999 STOCK INCENTIVE PLAN
                            (Full title of the Plans)

                                 Jay D. Browning
                 Vice President - Corporate Law and Secretary
                            Valero Energy Corporation
                                 One Valero Way
                            San Antonio, Texas 78249
                     (Name and address of agent for service)
  Telephone number, including area code, of agent for service: (210) 345-2000






                         CALCULATION OF REGISTRATION FEE
================================================================================
TITLE OF EACH                                PROPOSED    PROPOSED
   CLASS OF                                   MAXIMUM    MAXIMUM
SECURITIES TO                AMOUNT OF       OFFERING    AGGREGATE    AMOUNT OF
      BE                   SHARES TO BE      PRICE PER   OFFERING   REGISTRATION
  REGISTERED             REGISTERED(1)(2)     SHARE(3)   PRICE(3)      FEE(3)
-------------            ----------------    ---------   ---------  ------------
Common stock, Par value
$0.01 per share........  7,109,195 shares       N/A        N/A           N/A

Preferred Share Purchase
Rights(4)..............  

================================================================================
(1) The number of shares registered is based on an estimate of the maximum
    number of shares of common stock of Valero Energy Corporation ("Valero")
    issuable under the Premcor 2002 Special Stock Incentive Plan, Premcor 2002
    Equity Incentive Plan, and Premcor 1999 Stock Incentive Plan (collectively,
    the "Plans").

(2) Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the
    "Securities Act"), this registration statement shall be deemed to cover an
    indeterminate number of additional shares that may become issuable as a
    result of stock splits, stock dividends or similar transactions pursuant to
    the anti-dilution provisions of the Plans.

(3) The proposed maximum offering price was calculated and the fee was
    previously paid in connection with the filing with the U.S. Securities and
    Exchange Commission (the "SEC") of the Registration Statement on Form S-4 of
    Valero (File No. 333-125082) on May 20, 2005.

(4) No separate consideration will be received for the preferred share purchase
    rights.



                                       -2-



                             INTRODUCTORY STATEMENT

           Valero Energy Corporation, a Delaware corporation ("Valero" or the
"Registrant"), hereby amends its Registration Statement on Form S-4 (File No.
333-125082), which was declared effective on July 13, 2005 (the "Form S-4"), by
filing this Post-Effective Amendment No. 1 on Form S-8 relating to shares of
common stock, par value $0.01 per share, that are issuable by Valero upon the
exercise of stock options granted under the Premcor 2002 Special Stock Incentive
Plan, Premcor 2002 Equity Incentive Plan, and Premcor 1999 Stock Incentive Plan,
in each case of Premcor Inc. ("Premcor") (collectively, the "Plans"). All such
shares of Valero common stock were originally registered on the Form S-4.

           On September 1, 2005, Premcor merged with and into Valero pursuant to
the Agreement and Plan of Merger (the "Merger Agreement"), dated as of April 24,
2005, by and between Valero and Premcor. Pursuant to the Merger Agreement, at
the effective time of the merger, each share of common stock of Premcor issued
and outstanding immediately prior to the effective time of the merger, subject
to certain exceptions, was converted into the right to receive Valero common
stock or cash; shares of Premcor common stock that were converted into the right
to receive Valero common stock entitled the holder thereof to receive a number
of shares of Valero common stock (and associated preferred share purchase
rights) based on the exchange ratio of 0.99 shares of Valero common stock for
each such share of Premcor common stock exchanged in the merger. In addition,
each option to acquire shares of Premcor common stock granted pursuant to the
Plans that was outstanding and unexercised immediately prior to the effective
time was converted into an option to acquire shares of Valero common stock (and
associated preferred share purchase rights), as adjusted to reflect the exchange
ratio.


                                       -3-



                                     PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

Item 1.    PLAN INFORMATION.

Item 2.    REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.
           
           The documents containing the information specified in Item 1 of Form
S-8 and the statement of availability of information about Valero and any other
information required by Item 2 of Form S-8 will be sent or given to participants
in the Plans as specified by Rule 428 under the Securities Act. Such documents
are not required to be and are not filed with the SEC pursuant to Rule 424 of
the Securities Act and the Note to Part I of Form S-8. These documents and the
documents incorporated by reference in this Post-Effective Amendment pursuant to
Item 3 of Part II of Form S-8, taken together, constitute a prospectus that
meets the requirements of Section 10(a) of the Securities Act.

                                     PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.    INCORPORATION OF DOCUMENTS BY REFERENCE.

           The SEC allows Valero to incorporate by reference the information
that Valero discloses in its filings with the SEC. Incorporation by reference
means that Valero can disclose important information to you by referring you to
those documents. The information incorporated by reference is considered to be
part of this prospectus, and later information that Valero files with the SEC
will automatically update and supersede this information. The following
documents previously filed by Valero with the SEC pursuant to the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), are incorporated herein
by reference (all documents SEC File No. 001-13175):

     (a)    Annual Report on Form 10-K for the year ended December 31, 2004;

     (b)    Quarterly Report on Form 10-Q/A for the quarter ended March 31,
            2005;

     (c)    Quarterly Report on Form 10-Q for the quarter ended June 30, 2005;

     (d)    Current Reports on Form 8-K filed (i) February 3, 2005, (ii) March
            16, 2005, (iii) April 25, 2005, (iv) May 3, 2005, (v) May 12, 2005,
            (vi) May 25, 2005, (vii) June 17, 2005 (reporting information under 
            items 8.01 and 9.01), and (viii) June 20, 2005;

     (e)    Current Report on Form 8-K filed July 15, 2003, as amended by its
            Current Report on Form 8-K/A filed on August 12, 2003 and
            September 18, 2003.

     (f)    The description of Valero common stock and the preferred share
            purchase rights associated with Valero common stock contained in
            Valero's Form S-1 Registration Statement (File No. 333-27013) and
            Form 8-A Registration Statement (File No. 001-13175), and any
            amendments thereto filed for the purpose of updating such
            description.


                                       -4-


           Any document filed by Valero pursuant to Sections 13(a), 13(c), 14 or
15(d) of the Exchange Act subsequent to the date of this Registration Statement
and prior to the filing of a post-effective amendment which indicates that all
the securities offered hereby have been sold or that deregisters all the
securities then remaining unsold, shall be deemed to be incorporated by
reference in this Registration Statement and to be a part hereof from the date
of the filing of such document. Any statement incorporated by reference herein
shall be deemed to be modified or superseded for purposes of this Registration
Statement to the extent that a statement contained herein or in any other
subsequently filed document which also is or is deemed to be incorporated by
reference herein modifies or supersedes such statement. Any statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Registration Statement.

                                     EXPERTS

           The consolidated balance sheet of Valero Energy Corporation and
subsidiaries as of December 31, 2004, and the related statements of income,
stockholders' equity, cash flows and comprehensive income for the year then
ended, and management's assessment of the effectiveness of internal control over
financial reporting as of December 31, 2004, have been incorporated by reference
herein in reliance upon the reports of KPMG LLP, independent registered public
accounting firm, incorporated by reference herein, and upon the authority of
said firm as experts in accounting and auditing.

           The consolidated financial statements of Valero and subsidiaries at
December 31, 2003, and for each of the two years in the period ended December
31, 2003, appearing in Valero's Annual Report on Form 10-K for the year ended
December 31, 2004, have been audited by Ernst & Young LLP, independent
registered public accounting firm, as set forth in their report thereon included
therein and incorporated herein by reference. Such consolidated financial
statements are incorporated herein by reference in reliance upon such report
given on the authority of such firm as experts in accounting and auditing.

           The audited historical financial statements of Orion Refining
Corporation listed in the index appearing under Item 7(a) of Valero Energy
Corporation's Current Report on Form 8-K/A dated July 1, 2003 have been so
incorporated in reliance on the report of PricewaterhouseCoopers LLP,
independent accountants, given on the authority of said firm as experts in
auditing and accounting.

Item 4.    DESCRIPTION OF SECURITIES.

           Not applicable.

Item 5.    INTERESTS OF NAMED EXPERTS AND COUNSEL.

           In connection with the filing of the Registration Statement, Jay D.
Browning, Esq. has rendered an opinion to Valero upon the legality of the common
stock being registered hereunder. Mr. Browning beneficially owns shares of
common stock of Valero and options to purchase additional shares of Valero
common stock. At the time of rendering such opinion, Mr. Browning beneficially
owned 42,054 Valero shares and options to purchase 65,950 additional



                                       -5-


Valero shares, of which 50,284 are currently exercisable. Also at such time, Mr.
Browning was connected with Valero in that he was Vice President - Corporate Law
and Secretary of Valero.

Item 6.    INDEMNIFICATION OF DIRECTORS AND OFFICERS.

           Valero's Amended and Restated Certificate of Incorporation, as
amended (the "Restated Certificate of Incorporation") contains a provision that
eliminates the personal liability of a director to Valero and its stockholders
for monetary damages for breach of fiduciary duty as a director to the extent
currently allowed under the Delaware General Corporation Law. If a director were
to breach such duty in performing his duties as a director, neither Valero nor
its stockholders could recover monetary damages from the director, and the only
course of action available to Valero's stockholders would be equitable remedies,
such as an action to enjoin or rescind a transaction involving a breach of
fiduciary duty. To the extent certain claims against directors are limited to
equitable remedies, the provision in Valero's Restated Certificate of
Incorporation may reduce the likelihood of derivative litigation and may
discourage stockholders or management from initiating litigation against
directors for breach of their fiduciary duty. Additionally, equitable remedies
may not be effective in many situations. If a stockholder's only remedy is to
enjoin the completion of the Board of Directors' action, this remedy would be
ineffective if the stockholder does not become aware of a transaction or event
until after it has been completed. In such a situation, it is possible that the
stockholders and Valero would have no effective remedy against the directors.
Under Valero's Restated Certificate of Incorporation, liability for monetary
damages remains for (i) any breach of the duty of loyalty to Valero or its
stockholders, (ii) acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) payment of an
improper dividend or improper repurchase or redemption of Valero's stock under
Section 174 of the Delaware General Corporation Law, or (iv) any transaction
from which the director derived an improper personal benefit.

           Under Article V of the Restated Certificate of Incorporation and
Article VIII of Valero's Amended and Restated By-laws as currently in effect
(the "Restated By-laws") and an indemnification agreement with Valero's officers
and directors (the "Indemnification Agreement"), each person who is or was a
director or officer of Valero or a subsidiary of Valero, or who serves or served
any other enterprise or organization at the request of Valero or a subsidiary of
Valero, shall be indemnified by Valero to the full extent permitted by the
Delaware General Corporation Law.

           Under such law, to the extent that such person is successful on the
merits in defense of a suit or proceeding brought against him by reason of the
fact that he is or was a director or officer of Valero, or serves or served any
other enterprise or organization at the request of Valero, he shall be
indemnified against expenses (including attorneys' fees) actually and reasonably
incurred in connection with such action.

           Under such law, if unsuccessful in defense of a third-party civil
suit or a criminal suit, or if such suit is settled, such a person shall be
indemnified against both (a) expenses, including attorneys' fees, and (b)
judgments, fines and amounts paid in settlement if he acted in good faith and in
a manner he reasonably believed to be in, or not opposed to, the best interests
of Valero, and, with respect to any criminal action, had no reasonable cause to
believe his conduct was unlawful.



                                       -6-


           If unsuccessful in defense of a suit brought by or in the right of
Valero, or if such a suit is settled, such a person shall be indemnified under
such law only against expenses (including attorneys' fees) actually and
reasonably incurred in the defense or settlement of such suit if he acted in
good faith and in a manner he reasonably believed to be in, or not opposed to,
the best interests of Valero, except that if such person is adjudged to be
liable in such a suit for negligence or misconduct in the performance of his
duty to Valero, he cannot be made whole for expenses unless the court determines
that he is fairly and reasonably entitled to indemnity for such expenses.

           The Indemnification Agreement provides directors and officers with
specific contractual assurance that indemnification and advancement of expenses
will be available to them regardless of any amendments to or revocation of the
indemnification provisions of the Restated By-laws. The Indemnification
Agreement provides for indemnification of directors and officers against both
stockholder derivative claims and third-party claims. Sections 145(a) and 145(b)
of the Delaware General Corporation Law, which grant corporations the power to
indemnify directors and officers, specifically authorize lesser indemnification
in connection with derivative claims than in connection with third-party claims.
The distinction is that Section 145(a), concerning third-party claims,
authorizes expenses and judgments and amounts paid in settlement (as is provided
in the Indemnification Agreement), while Section 145(b), concerning derivative
suits, generally authorizes only indemnification of expenses. However, Section
145(f) expressly provides that the indemnification and advancement of expenses
provided by or granted pursuant to the subsections of Section 145 shall not be
exclusive of any other rights to which those seeking indemnification or
advancement of expenses may be entitled under any agreement. No Delaware case
directly answers the question whether Delaware's public policy would support
this aspect of the Indemnification Agreement under the authority of Section
145(f), or would cause its invalidation because it does not conform to the
distinctions contained in Sections 145(a) and 145(b).

           Delaware corporations also are authorized to obtain insurance to
protect officers and directors from certain liabilities, including liabilities
against which the corporation cannot indemnify its directors and officers.
Valero currently has in effect a directors' and officers' liability insurance
policy.

Item 7.    EXEMPTION FROM REGISTRATION CLAIMED.

           Not applicable.

Item 8.    EXHIBITS.

4.1   Description of Valero's common stock and preferred share purchase rights
      (contained in Item 3(f) of Part II of this Form S-8)

5.1   Opinion of Jay D. Browning, Esq., as to the legality of the securities
      being registered (including Consent of Counsel)*

23.1  Consent of KPMG LLP, San Antonio, Texas*

23.2  Consent of Ernst & Young LLP, San Antonio, Texas*



                                       -7-


23.3  Consent of PricewaterhouseCoopers LLP, New Orleans, Louisiana*

23.4  Consent of Counsel (included in Exhibit 5.1)*

24.1  Power of Attorney (contained in the Form S-4 previously filed on May 20,
      2005)

* Filed herewith

Item 9.    UNDERTAKINGS.

     (a)   The undersigned Registrant hereby undertakes:

          (1)   To file, during any period in which offers or sales are being
made, a post-effective amendment to this Registration Statement:

               (i)   To include any prospectus required by Section 10(a)(3) of
     the Securities Act;

               (ii)  To reflect in the prospectus any facts or events arising
     after the effective date of the Registration Statement (or the most recent
     post-effective amendment thereof) which, individually or in the aggregate,
     represent a fundamental change in the information set forth in the
     Registration Statement. Notwithstanding the foregoing, any increase or
     decrease in the volume of securities offered (if the total dollar value of
     securities offered would not exceed that which was registered) and any
     deviation from the low or high end of the estimated maximum offering range
     may be reflected in the form of a prospectus filed with the SEC pursuant
     to Rule 424(b) if, in the aggregate, the changes in volume and price
     represent no more than a 20% change in the maximum aggregate offering
     price set forth in the "Calculation of Registration Fee" table in the
     effective Registration Statement;

               (iii) To include any material information with respect to the
     plan of distribution not previously disclosed in the Registration Statement
     or any material change to such information in the Registration Statement;

     Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply
     if the information required to be included in a post-effective amendment
     by those paragraphs is contained in periodic reports filed with or
     furnished to the SEC by the Registrant pursuant to Section 13 or Section
     15(d) of the Exchange Act that are incorporated by reference in the
     Registration Statement.

          (2)   That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

          (3)   To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.



                                       -8-


     (b)   The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or 15(d) of the Exchange
Act (and, where applicable, each filing of an employee benefit plan's annual
report pursuant to Section 15(d) of the Exchange Act) that is incorporated by
reference in the Registration Statement shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

     (c)   Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the Registrant pursuant to the foregoing provisions, or otherwise, the
Registrant has been advised that in the opinion of the SEC such indemnification
is against public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Registrant of expenses incurred or
paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.


                                       -9-



                                   SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on a Form S-8 and has duly caused this post-effective
amendment no. 1 on Form S-8 to the registration statement on Form S-4 to be
signed on its behalf by the undersigned, thereunto duly authorized, in the city
of San Antonio, State of Texas, on September 1, 2005.

                                    VALERO ENERGY CORPORATION


                                    By     /s/  Michael S. Ciskowski           
                                        ------------------------------------
                                        Name:   Michael S. Ciskowski
                                        Title:  Executive Vice President and
                                                Chief Financial Officer


      Pursuant to the requirements of the Securities Act of 1933, as amended,
this post-effective amendment no. 1 on Form S-8 to the registration statement on
Form S-4 has been signed below by the following persons in the capacities
indicated on September 1, 2005.

       SIGNATURE                          TITLE

                            Chairman, Chief Executive Officer
         *                             and Director
---------------------        (Principal Executive Officer)
William E. Greehey            

         *                     Executive Vice President and
---------------------             Chief Financial Officer
Michael S. Ciskowski       (Principal Financial and Accounting
                                        Officer)

         *                               Director
---------------------
  E. Glenn Biggs

         *                               Director
---------------------
   W.E. Bradford

         *                               Director
---------------------
 Ronald K. Calgaard

         *                               Director
---------------------
   Jerry D. Choate

         *                               Director
---------------------
 Ruben M. Escobedo



                                       -10-



         *                               Director
---------------------
    Bob Marbut

         *                               Director
---------------------
 Donald L. Nickles

         *                               Director
---------------------
Susan Kaufman Purcell



*By: /s/ Jay D. Browning
     -------------------
         Jay D. Browning
        Attorney-in-Fact

                                       -11-



                                  EXHIBIT INDEX

EXHIBIT     DESCRIPTION
-------     -----------

4.1         Description of Valero's common stock and preferred share purchase
            rights (contained in Item 3(f) of Part II of this Form S-8)

5.1         Opinion of Jay D. Browning, Esq., as to the legality of
            the securities being registered (including Consent of
            Counsel)

23.1        Consent of KPMG LLP, San Antonio, Texas

23.2        Consent of Ernst & Young LLP, San Antonio, Texas

23.3        Consent of PricewaterhouseCoopers LLP, New Orleans,
            Louisiana

23.4        Consent of Counsel (included in Exhibit 5.1)

24.1        Power of Attorney (contained in the Form S-4 previously
            filed on May 20, 2005)



                                       -12-