FIRST
AMENDMENT


TO


THIRD AMENDED AND RESTATED
REVOLVING CREDIT AGREEMENT











This
First Amendment to Third Amended and Restated Revolving Credit Agreement (this
“Amendment”),
dated as of March 3, 2008, is entered into by (1) FRONTIER OIL AND REFINING
COMPANY, a Delaware corporation (the “Borrower”),
(2) FRONTIER OIL CORPORATION, a Wyoming corporation (“FOC”), (3)
each of the financial institutions party to the Credit Agreement referred to
below (the “Lenders”)
and (4) UNION BANK OF CALIFORNIA, N.A., a national banking association, as
administrative agent (the “Administrative
Agent”) for the Lenders.








Recitals





A.           The
Borrower, FOC, the Lenders, the Administrative Agent and BNP Paribas, a French
banking corporation, as syndication agent, are party to a Third Amended and
Restated Revolving Credit Agreement dated as of October 1, 2007 (the “Credit
Agreement”). Terms defined in the Credit Agreement and not otherwise
defined herein have the same respective meanings when used herein, and the rules
of interpretation set forth in Section 1.3 of the Credit Agreement are
incorporated herein by reference.





B.           The
Borrower, FOC, the Lenders and the Administrative Agent wish to amend the Credit
Agreement to, among other things, permit the Borrower to incur indebtedness to
Utexam Limited of up to $300,000,000 (plus the amount of any related
transportation costs and expenses) at any time outstanding, in respect of crude
oil purchases and related transactions. Accordingly, for good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
Borrower, FOC, the Lenders and the Administrative Agent hereby agree as set
forth below.








SECTION
1.  Amendments to Credit
Agreement .
 Effective as of the date hereof but subject to satisfaction of the
conditions precedent set forth in Section 2 of this Amendment, the Borrower, FOC
and the Lenders hereby agree that the Credit Agreement is amended as set forth
below.





(a)  Section
7.3 of the Credit Agreement is amended by (i) inserting the word “and” after the
semicolon at the end of clause (c) thereof, (ii) deleting “; and” at the end of
clause (d) thereof and substituting a period and (iii) deleting clause (e)
thereof.





(b)  Section
7.4(k) of the Credit Agreement is amended in full to read as
follows:





“(k)           the
Debt of the Borrower, as purchaser, and FOC, as guarantor, in respect of the
Utexam Transactions, provided that such Debt does not exceed, at any time
outstanding, the sum of $300,000,000 plus the amount of any related
transportation costs and expenses;”





SECTION
2.  Conditions
Precedent . 
This Amendment shall become effective as of the date first set forth above when
and if the Administrative Agent receives all of the following, each dated the
date hereof, in form and substance satisfactory to the Administrative Agent and
in the number of originals requested thereby:





(a)  this
Amendment, duly executed by the Borrower, FOC and the Lenders; and





(b)  a consent
to this Amendment, duly executed by the Guarantors and by the Borrower, in its
capacity as guarantor under the Borrower Guaranty.





SECTION
3.  Representations and
Warranties .
 Each of the Borrower and FOC represents and warrants to the Lenders and
the Administrative Agent as set forth below.





(a)  The
execution, delivery and performance by each of the Borrower and FOC of this
Amendment and the Credit Agreement, as amended hereby, and the consummation of
the transactions contemplated hereby and thereby, are within such Credit Party’s
legal powers, have been duly authorized by all necessary legal action and do not
(i) contravene such Credit Party’s charter documents or bylaws, (ii) violate any
Governmental Rule, (iii) conflict with or result in the breach of, or constitute
a default under, any Material Contract, loan agreement, indenture, mortgage,
deed of trust or lease, or any other contract or instrument, binding on or
affecting such Credit Party, any of its Subsidiaries or any of their respective
properties, the conflict, breach or default of which could reasonably be
expected to have a Material Adverse Effect, or (iv) result in or require the
creation or imposition of any Lien upon or with respect to any of the properties
of such Credit Party or any of its Subsidiaries, except for Liens created or
permitted under the Credit Documents, as amended hereby. Neither such Credit
Party nor any of its Subsidiaries is in violation of any Governmental Rule or in
breach of any such contract, loan agreement, indenture, mortgage, deed of trust,
lease or other contract or instrument, the violation or breach of which could
reasonably be expected to have a Material Adverse Effect.





(b)  No
Governmental Action, and no authorization, approval or other action by, or
notice to, any third party, is required for the due execution, delivery or
performance by the Borrower or FOC of this Amendment or the Credit Agreement, as
amended hereby, or for the consummation of the transactions contemplated hereby
or thereby, except for (i) authorizations, approvals and other actions by, and
notices to, third parties, the failure to obtain which could not reasonably be
expected to have a Material Adverse Effect, and (ii) Governmental Action that
has been duly obtained, taken, given or made and is in full force and
effect.





(c)  This
Amendment and the Credit Agreement, as amended hereby, have been duly executed
and delivered by the Borrower and FOC. This Amendment and the Credit Agreement,
as amended hereby, are the legal, valid and binding obligations of the Borrower
and FOC, enforceable against each such Credit Party in accordance with their
respective terms, except as the enforceability hereof or thereof may be limited
by bankruptcy, insolvency, moratorium, reorganization or other similar laws
affecting creditors’ rights generally or by equitable principles relating to
enforceability.





(d)  Each of
the Security Agreement and the Stock Pledge Agreement constitutes a valid and
perfected first-priority Lien on the Collateral purported to be encumbered
thereby, enforceable against all third parties in all jurisdictions, and secures
the payment of all obligations of the Borrower or FRMI, as applicable, under the
Credit Documents, as amended hereby, to which the Borrower or FRMI, as
applicable, is a party, and the execution, delivery and performance of this
Amendment do not adversely affect the Lien of the Security Agreement or the
Stock Pledge Agreement.





(e)  There has
been no amendment to the charter documents or bylaws of the Borrower on or after
September 20, 2007 or of FOC on or after September 21, 2007. The representations
and warranties contained in each Credit Document, as amended hereby, to which
the Borrower and/or FOC is a party are correct in all material respects on and
as of the date hereof, before and after giving effect to this Amendment, as
though made on and as of the date hereof. No event has occurred and is
continuing, or would result from the effectiveness of this Amendment, that
constitutes a Default.





SECTION
4.  Reference to and Effect on
Credit Documents .





(a)           On
and after the effective date of this Amendment, each reference in the Credit
Agreement to “this Agreement,” “hereunder,” “hereof,” “herein” or words of like
import referring to the Credit Agreement, and each reference in the other Credit
Documents to “the Credit Agreement,” “thereunder,” “thereof,” “therein” or words
of like import referring to the Credit Agreement, shall mean and be a reference
to the Credit Agreement as amended by this Amendment.





(b)           Except
as specifically amended above, the Credit Agreement and the other Credit
Documents shall remain in full force and effect and are hereby ratified and
confirmed. Without limiting the generality of the foregoing, the Security
Agreement and the Stock Pledge Agreement and all of the Collateral described
therein do and shall continue to secure the payment of all obligations under the
Credit Documents, as amended hereby, stated to be secured thereby.





(c)           The
execution, delivery and effectiveness of this Amendment shall not operate as a
waiver of any right, power or remedy of the Administrative Agent or any Lender
under any of the Credit Documents or constitute a waiver of any provision of any
of the Credit Documents.





SECTION
5.  Costs and
Expenses . 
The Borrower agrees to pay on demand all costs and expenses of the
Administrative Agent in connection with the preparation, execution and delivery
of this Amendment and the other instruments and documents to be delivered
hereunder, including the reasonable fees and out-of-pocket expenses of counsel
for the Administrative Agent with respect thereto and with respect to advising
the Administrative Agent as to its rights and responsibilities hereunder and
thereunder.





SECTION
6.  Execution in
Counterparts . 
This Amendment may be executed in any number of counterparts and by the parties
hereto in separate counterparts, each of which when so executed and delivered
shall be deemed to be an original and all of which taken together shall
constitute one and the same agreement. Delivery of an executed counterpart of a
signature page to this Amendment by telecopier shall be effective as delivery of
an originally executed counterpart of this Amendment.














[The
remainder of this page has been left blank intentionally.]








SECTION
7.  Governing
Law .
 THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED AND ENFORCED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF CALIFORNIA APPLICABLE TO CONTRACTS
MADE AND PERFORMED IN THE STATE OF CALIFORNIA.





The
parties hereto have caused this Amendment to be executed by their respective
duly authorized representatives as of the date first written above.








FRONTIER
OIL AND REFINING COMPANY








By: /s/ Leo
Hoonakker


Name: Leo
Hoonakker


Title:
VP &
Treasurer











FRONTIER
OIL CORPORATION








By: /s/ Doug
Aron


Name:  Doug
Aron


Title:
VP – Corporate
Finance











UNION
BANK OF CALIFORNIA, N.A.,


as
Administrative Agent and Lender








By:  /s/ Timothy
Brendel


Name:  Timothy
Brendel


Title:
Assistant Vice
President











BNP
PARIBAS








By: /s/ Betsy
Jocher


Name:  Betsy
Jocher


Title:
Director








By: /s/ Richard
Hawthorne


Name: Richard
Hawthorne


Title:
Vice
President











TORONTO
DOMINION (TEXAS) LLC








By: /s/ Debbi L.
Brito


Name: Debbi L .
Brito


Title:
Authorized
Signatory











WELLS
FARGO BANK, N.A.








By: /s/ Oleg
Kogan


Name: Oleg
Kogan


Title:
Assistant Vice
President











BANK OF
SCOTLAND








By: /s/ Karen
Weich


Name:  Karen
Weich


Title:
Vice
President











U.S. BANK
NATIONAL ASSOCIATION








By: /s/ Monte E.
Deckerd


Name:  Monte
Deckerd


Title:
Senior Vice
President











THE FROST
NATIONAL BANK








By: /s/ Thomas H.
Duncan


Name:
Thomas H.
Duncan


Title:
Sr. Vice
President











CAPITAL
ONE, NATIONAL ASSOCIATION








By: /s/ Nancy
Mak


Name:  Nancy
Mak


Title:
Assistant Vice
President