EXHIBIT 4.6

                             SUPPLEMENTAL INDENTURE

         SUPPLEMENTAL INDENTURE dated as of April 3, 2002, among Giant
Industries, Inc., a corporation duly organized and existing under the laws of
the State of Delaware (the "Company"), the Subsidiary Guarantors listed as
signatories hereto (the "Subsidiary Guarantors"), and The Bank of New York, a
banking corporation duly organized and existing under the laws of the State of
New York, as Trustee (the "Trustee").

         WHEREAS, the Company, the Subsidiary Guarantors and the Trustee have
heretofore executed and delivered an Indenture dated as of August 26, 1997, as
supplemented (the "Indenture"), providing for the issuance from time to time of
its 9% Senior Subordinated Notes due 2007;

         WHEREAS, Section 9.02 of the Indenture provides that the Company, the
Subsidiary Guarantors and the Trustee may amend the Indenture with the consent
of the Holders of at least a majority in principal amount of the then
outstanding Securities (such term and each other capitalized term used in this
First Supplemental Indenture and not defined herein having the meanings assigned
thereto in the Indenture);

         WHEREAS, the Company and the Subsidiary Guarantors desire to amend the
Indenture, as set forth in Article I hereof;

         WHEREAS, the Holders of at least a majority in aggregate principal
amount of the Securities outstanding have consented to the amendments effected
by this Supplemental Indenture; and

         WHEREAS, this Supplemental Indenture has been duly authorized by all
necessary corporate action on the part of the Company and the Subsidiary
Guarantors.

         NOW, THEREFORE, the Company, the Subsidiary Guarantors and the Trustee
agree as follows for the equal and ratable benefit of the Holders of the
Securities:

                                    ARTICLE I
                                    AMENDMENT

SECTION 1.01. Amendment to Section 1.01. The definition of "Restricted Payment"
in Section 1.01 of the Indenture is hereby amended by deleting clause (iii) of
said definition and adding in lieu thereof the following:

         "(iii) the making of any principal payment on, or the purchase,
         defeasance, repurchase, redemption or other acquisition or retirement
         for value, prior to any scheduled maturity, scheduled repayment or
         scheduled sinking fund payment, of any Indebtedness which is pari passu
         or subordinated in right of payment to the Securities, except that any
         such payment, purchase, defeasance, repurchase, redemption or other
         acquisition or

         retirement for value of pari passu Indebtedness shall not constitute a
         Restricted Payment unless the Indebtedness, if any, incurred to
         refinance such pari passu Indebtedness is senior in right of payment to
         the Securities or has any scheduled principal payment prior to the
         maturity date of the Securities;"

                                   ARTICLE II
                                  MISCELLANEOUS

         SECTION 2.01. Interpretation; Severability; Headings. Upon the
execution and delivery of this Supplemental Indenture, the Indenture shall be
modified and amended in accordance with this Supplemental Indenture, and all the
terms and conditions of both shall be read together as though they constitute
one instrument, except that, in case of conflict, the provisions of this
Supplemental Indenture will control. The Indenture, as modified and amended by
this Supplemental Indenture, is hereby ratified and confirmed in all respects
and shall bind every Holder of Securities. In case of conflict between the terms
and conditions contained in the Securities and those contained in the Indenture,
as modified and amended by this Supplemental Indenture, the provisions of the
Indenture, as modified and amended by this Supplemental Indenture, shall
control. In case 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. The
Article and Section headings of this Supplemental Indenture have been inserted
for convenience of reference only, are not to be considered a part hereof and
shall in no way modify or restrict any of the terms or provisions hereof.

         SECTION 2.02. Conflict with TIA. If any provision of this Supplemental
Indenture limits, qualifies or conflicts with any provision of the TIA that is
required under the TIA to be part of and govern any provision of this
Supplemental Indenture, the provision of the TIA shall control. If any provision
of this Supplemental Indenture modifies or excludes any provision of the TIA
that may be so modified or excluded, the provision of the TIA shall be deemed to
apply to the Indenture as so modified or to be excluded by this Supplemental
Indenture, as the case may be.

         SECTION 2.03. Successors; Benefits of Supplemental Indenture, etc. All
agreements of the Company and the Subsidiary Guarantors in this Supplemental
Indenture shall bind their respective successors. All agreements of the Trustee
in this Supplemental Indenture shall bind its successors. Nothing in this
Supplemental Indenture or the Securities, express or implied, shall give to any
Person, other than the parties hereto and thereto and their successors hereunder
and thereunder and the Holders of the Securities, any benefit of any legal or
equitable right, remedy or claim under the Indenture, this Supplemental
Indenture or the Securities.

         SECTION 2.04. Certain Duties and Responsibilities of the Trustee;
Trustee Not Responsible for Recitals. In entering into this Supplemental
Indenture, the Trustee shall be entitled to the benefit of every provision of
the Indenture relating to the conduct or affecting the liability or affording
protection to the Trustee, whether or not elsewhere herein so provided. The
Trustee shall not be responsible in any manner whatsoever for or in respect of
the validity or


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sufficiency of this Supplemental Indenture or for or in respect of the recitals
contained herein, all of which recitals are made solely by the Company and the
Subsidiary Guarantors.

         SECTION 2.05. Governing Law. This Supplemental Indenture shall be
construed in accordance with the laws of the State of New York without reference
to its conflict of law provisions, and the obligations, rights and remedies of
the parties hereunder shall be determined in accordance with such laws.

         SECTION 2.06. Duplicate Originals. All parties may sign any number of
copies or counterparts of this Supplemental Indenture. Each signed copy or
counterpart shall be an original, but all of them together shall represent the
same agreement.

         IN WITNESS WHEREOF, each party hereto has caused this Supplemental
Indenture to be signed by its officer thereunto duly authorized as of the date
first written above.

                        GIANT INDUSTRIES, INC.,


                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                        THE BANK OF NEW YORK, as Trustee,


                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                        SUBSIDIARY GUARANTORS

                        Giant Industries Arizona, Inc., an Arizona corporation

                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                        Ciniza Production Company, a New Mexico
                        corporation

                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                                       3

                        Giant Stop-N-Go of New Mexico, Inc., a New Mexico
                        corporation


                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                        Giant Four Corners, Inc., an Arizona corporation

                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                        Phoenix Fuel Co., Inc., an Arizona corporation

                             By /s/
                                ------------------------------------
                                Name:
                                Title:


                        San Juan Refining Company, a New Mexico corporation


                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                        Giant Mid-Continent, Inc., an Arizona corporation

                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                        Giant Pipeline Company, a New Mexico corporation

                             By /s/
                                ------------------------------------
                                Name:
                                Title:

                                       4

                        DeGuelle Oil Company, a Colorado corporation

                             By /s/
                                ------------------------------------
                                Name:
                                Title:



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