FIFTH AMENDMENT
                               TO
            REVOLVING CREDIT AND LETTER OF CREDIT AGREEMENT




     This Amendment, dated as of July 1, 1995, is entered into by
(1) FRONTIER OIL AND REFINING COMPANY, a Delaware corporation
(the "Borrower"), (2) the banks parties to the Credit Agreement
referred to below (the "Banks") and (3) UNION BANK, a California
banking corporation, as agent (the "Agent") for the Banks.


Recitals

     A.   The Borrower, the Banks and the Agent have entered into
a Revolving Credit and Letter of Credit Agreement dated as of
August 10, 1992, as amended by a letter of waiver and amendment
dated March 17, 1993, a Second Amendment to Revolving Credit and
Letter of Credit Agreement dated as of April 30, 1993, a Third
Amendment to Revolving Credit and Letter of Credit Agreement
dated as of December 31, 1993 and a Fourth Amendment to Revolving
Credit and Letter of Credit Agreement dated as of July 6, 1994
(said Agreement, as so amended, herein called 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
Sections 1.2 and 1.3 of the Credit Agreement are incorporated
herein by reference.

     B.   The Borrower, the Banks and the Agent hereby agree as
set forth below.

     Section 1.  Amendments to Credit Agreement.  Effective as of
the date first set forth above and subject to satisfaction of the
conditions precedent set forth in Section 2, the Credit Agreement
is hereby amended as follows:

        (a)   The definition of "Commitment Termination Date" in
Section 1.1 of the Credit Agreement is amended in full to read as
follows:

              "'Commitment Termination Date' means April 2, 1997;
provided, however, that, upon (a) written request by the Borrower
not later than May 15, 1996 and (b) notice of such extension by
the Agent to the Borrower not later than July 15, 1996, the
Commitment Termination Date may be extended by the Agent and the
Banks, in their sole and absolute discretion, for up to an
additional year; and further provided, however, that the Agent's
failure to notify the Borrower of any such extension by the
applicable date referred to above shall constitute a denial of
such extension."

        (b)   Sections 2.1(a) and 2.7(b) of the Credit Agreement
are amended by deleting the words and figures "fifteen million
dollars ($15,000,000)" in each such section and substituting the
words and figures "twenty million dollars ($20,000,000)" in each
instance.

        (c)   Section 2.2(a) of the Credit Agreement is amended
by deleting the words and figures "four hundred twenty-five
thousandths percent (.425%)" and substituting the words and
figures "four-tenths percent (0.4%)."

        (d)   Section 2.6(a) of the Credit Agreement is amended
by deleting the words and figures "one and one-quarter percent
(1.25%)" in clause (i) thereof and "two and one-quarter percent
(2.25%)" in clause (ii) thereof and substituting the words and
figures "seven-eighths percent (0.875%)" and "two percent
(2.00%)," respectively.

        (e)   Section 2.12(a) of the Credit Agreement is amended
by deleting the words and figures "one and one-half percent
(1.50%)" and substituting the words and figures "one and one-
quarter percent (1.25%)."

        (f)   Schedule 3 to the Credit Agreement is deleted and
replaced by Schedule 3 to this Amendment.

     Section 2.   Conditions to Effectiveness.  This Amendment
shall become effective as of the date first set forth above when
the Agent has received a renewal fee of $125,000 for the account
of the Banks and all of the following documents, each dated on or
before the date hereof, in form and substance satisfactory to the
Agent and in the number of originals requested by the Agent:

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

        (b)   an amendment to the FOC Guaranty with respect to
the liquidity coverage covenant contained in Section 7.2(k)
thereof, duly executed by FOC and the Banks, together with the
other documents required to be delivered to the Agent as
conditions precedent to the effectiveness of such amendment;

        (c)   an amendment and restatement of the Agent's Fee
Letter;

        (d)   a consent to this Amendment, duly executed by
Wainoco and the Guarantors;

        (e)   copies of the resolutions of the Board of Directors
of the Borrower approving this Amendment and any documents
delivered by the Borrower pursuant hereto, certified by the
Secretary or an Assistant Secretary of the Borrower to be correct
and complete and in full force and effect as of the date of
execution, and as of the effective date, of this Amendment;

        (f)   a certificate of the Secretary or an Assistant
Secretary of the Borrower as to the incumbency, and setting forth
a specimen signature, of each of the persons who has signed this
Amendment or any document delivered by the Borrower pursuant
hereto;

        (g)   a certificate of the Borrower, signed on behalf of
the Borrower by its President or a Vice President and its
Secretary or any Assistant Secretary, certifying as to (A) the
absence of any amendments to the charter documents or bylaws of
the Borrower on or after August 18, 1992, (B) the truthfulness in
all material respects of the representations and warranties
contained in the Credit Documents as though made on and as of the
effective date of this Amendment and (C) the absence of any event
occurring and continuing, or resulting from the effectiveness of
this Amendment, that constitutes a Default or an Event of
Default; and

        (h)   such other approvals, opinions and documents as the
Agent may reasonably request.

     Section 3.  Representations and Warranties of Borrower.  The
Borrower represents and warrants as follows:

        (a)   The Borrower is a corporation duly organized,
validly existing and in good standing under the laws of the State
of Delaware. 

        (b)  The execution, delivery and performance by the
Borrower of this Amendment and the Credit Documents, as amended
hereby, to which it is or is to be a party are within the
Borrower's corporate powers, have been duly authorized by all
necessary corporate action and do not (i) contravene the
Borrower's charter documents or bylaws, (ii) contravene any
Governmental Rule or contractual restriction binding on or
affecting the Borrower or (iii) result in or require the creation
or imposition of any Lien or preferential arrangement of any
nature (other than any created by the Credit Documents) upon or
with respect to any of the properties now owned or hereafter
acquired by the Borrower.

        (c)  No Governmental Action is required for the due
execution, delivery or performance by the Borrower of this
Amendment or any of the Credit Documents, as amended hereby, to
which the Borrower is or is to be a party.

        (d)  This Amendment and each of the Credit Documents, as
amended hereby, to which the Borrower is a party constitute
legal, valid and binding obligations of the Borrower enforceable
against the Borrower in accordance with their respective terms.

        (e)  The Security Agreement, the Account Pledge Agreement
and the Note Pledge Agreement constitute valid and perfected
first-priority Liens on the Collateral covered thereby,
enforceable against all third parties in all jurisdictions, and
secure the payment of all obligations of the Borrower under the
Credit Documents, as amended hereby; and the execution, delivery
and performance of this Amendment do not adversely affect the
Lien of the Security Agreement, the Account Pledge Agreement or
the Note Pledge Agreement.

        (f)  The consolidated balance sheet of FOC and its
Subsidiaries as of December 31, 1994 and the related consolidated
statements of income, retained earnings and cash flows of FOC and
its Subsidiaries for the fiscal year then ended, certified by
Arthur Andersen & Co., independent public accountants, and the
report as of April 30, 1995 referred to in Section 7.1(j)(i) of
the FOC Guaranty, certified by the chief financial officer or
chief accounting officer of FOC, fairly present the consolidated
financial condition of FOC and its Subsidiaries as of such dates
and the consolidated results of the operations of FOC and its
Subsidiaries for the fiscal periods ended on such dates, all in
accordance with generally accepted accounting principles applied
on a consistent basis.  Since April 30, 1995 there has been no
material adverse change in the business, condition (financial or
otherwise), operations, performance, properties or prospects of
FOC or any of its Subsidiaries.  FOC and its Subsidiaries have no
material contingent liabilities except as disclosed in such
financial statements or the notes thereto.

        (g)  There is no pending or, to the knowledge of the
Borrower, threatened action or proceeding affecting FOC or any
its Subsidiaries before any Governmental Person or arbitrator
that may materially and adversely affect the financial condition
or operations of FOC or any of its Subsidiaries or that purports
to affect the legality, validity or enforceability of this
Amendment or any of the Credit Documents, as amended hereby.

     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 any other expression of like
import referring to the Credit Agreement, and each reference in
the other Credit Documents to "the Credit Agreement,"
"thereunder," "thereof," "therein" or any other expression 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 or referred to 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, the Account Pledge Agreement and the Note Pledge
Agreement, and all of the Collateral described therein, do and
shall continue to secure the payment of all obligations of the
Borrower under the Credit Documents, as amended hereby.

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

     Section 5.  Costs, Expenses and Taxes.  The Borrower agrees
to pay on demand all costs and expenses of the 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 Agent with respect thereto and with
respect to advising the Agent as to its rights and
responsibilities hereunder and thereunder.  In addition, the
Borrower shall pay any and all stamp and other taxes payable or
determined to be payable in connection with the execution and
delivery of this Amendment and the other instruments and
documents to be delivered hereunder, and the Borrower agrees to
save the Agent and each Bank harmless from and against any and
all liabilities with respect to or resulting from any delay in
paying or omission to pay such taxes.

     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 instrument.

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


FRONTIER OIL AND REFINING COMPANY



By:  /s/ Jon D. Galvin
     ------------------------------
     Jon D. Galvin
     Vice President and 
      Chief Financial Officer



UNION BANK, as Agent and 
  as a Bank



By: /s/ Richard P. DeGrey, Jr.
    ------------------------------
    Richard P. DeGrey, Jr.
    Vice President



BANQUE PARIBAS



By:  /s/ Mark M. Green
     ------------------------------
Name: Mark M. Green
Title: Vice President



By:  /s/ Barton D. Schouest
     ------------------------------
Name: Barton D. Schouest
Title: Group Vice President



DEN NORSKE BANK AS



By:  /s/ Theodore S. Jadick, Jr.
     ------------------------------
Name: Theodore S. Jadick, Jr.
Title: Senior Vice President



By:  /s/ Fran Meyers
     ------------------------------
Name: Fran Meyers
Title: Vice President


SCHEDULE 3

METHODS OF CALCULATION OF FAIR MARKET VALUE OF INVENTORY


     In determining market value of Inventory, the actual
Eligible Inventory volumes shall be multiplied by the prices
determined below for each category of Inventory.  Each price
derived from the independent sources described below shall be the
price for the relevant Inventory type published on the effective
date, or published most recently before the effective date, of
the Borrowing base Certificate concerned.

Inventory Type                  Method of Determining Prices
- ----------------------------    ---------------------------------

Sweet Wyoming Crude             Average of Texaco's and Conoco's  
                                posted price, less gravity        
                                adjustment ("ATCPPLGA"), for 40-
                                degree Sweet Wyoming Crude, plus  
                                $2.20/barrel.

General Wyoming Sour Crude      ATCPPLGA for 24-degree General    
                                Wyoming Sour Crude, plus          
                                $3.30/barrel.

Wyoming Asphaltic Sour          ATCPPLGA for 21-degree Wyoming
  Sour Crude                    Asphaltic Sour Crude, plus        
                                $2.00/barrel.

Canadian Sour Crude (MSO)       New York Mercantile Exchange near 
                                month contract closing price for
                                West Texas Intermediate Crude,
                                less gravity adjustment if pro-
                                vided for in crude purchase 
                                contract terms ("NYMEXWTILGA"),
                                minus $1.20/barrel.

Bow River Sour Crude            NYMEXWTILGA, minus $1.60/barrel.

Mixed Monty Sour                ATCPPLGA for Sweet Wyoming Crude.

Finished Gasoline               70% times Denver OPIS Low*,
                                  less $.014/gal.
                                +30% times Cheyenne OPIS Los*,
                                  less $.01/gal.

Diesel                          60% times Denver OPIS Low*,
                                  less $.015/gal.
                                +40% times Cheyenne OPIS Low*,
                                  less $.01/gal.

Asphalt                         For volumes of Asphalt that have
                                been committed for sale under a
                                binding sales contract, the
                                contract price (converted to a
                                price per barrel by dividing the
                                contract short-ton price by 5.6).
                                For all other Asphalt volumes,
                                the average of the high and low
                                Asphalt Cement dollars/ton price
                                (divided by 5.6 to convert the
                                short-ton price to a price per
                                barrel), as established in the
                                category ASPHALT SELLING PRICES
                                Area Barge for MID-CONTINENT/MID-
                                WEST in Asphalt Weekly Monitor,
                                published by Poten & Partners (in
                                the absence of this source of
                                pricing information, such price
                                as determined by the Agent).

Gas Oil                         70% times the Unleaded Regular
                                  Gasoline Net Price
                                +30% times the #2 Diesel net
                                price, less $.10/gal.

Sulfur                          Frontier's net-back price, based
                                on Frontier's most recent sale to
                                an independent third party.

Coke                            $0.00/ton

Propane                         Conway, Kansas OPIS wholesale
                                Propane price, plus $.05/gal.

Normal Butane                   Same methodology as Propane
                                except use Butane price.

Field Butane                    Same as Normal Butane price.

Iso Butane                      Same methodology as Propane 
                                except use Iso Butane price.

Olefins                         Same net price used for Premium
                                Unleaded Gasoline, less
                                $.156/gal.

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

*     As the price applies to each grade of gasoline (Unleaded
Regular, Unleaded Mid-Grade, Unleaded Premium and Leaded Regular)
or diesel (#1 Diesel (0.05% sulfur), #1 Diesel (0.5% sulfur), #2
Diesel (0.05% sulfur) and #2 Diesel (0.5% sulfur)).

Light Straight Run              Same as net price used for 
                                Unleaded Regular Gasoline.

Reformate                       Same as net price used for
                                Unleaded Regular Gasoline.


Cat Gas                         Same as net price used for
                                Premium Unleaded Gasoline.

Naphtha and Raffinate           Same as net price used for
                                Unleaded Regular Gasoline,
                                less $.04/gal.

MTBE                            Most recent price the Borrower
                                paid to an independent third
                                party for MTBE.

Ethanol                         Most recent price the Borrower
                                paid to an independent third
                                party for Ethanol.

Natural Gasoline                Conway, Kansas OPIS wholesale
                                price of Natural Gasoline, plus
                                $.05/gal.

Raw Distillate Oil              If the Borrower is selling #2
                                Diesel (0.5% sulfur), then the
                                net price for #2 Diesel (0.5%
                                sulfur), less $.02/gal.  If the
                                Borrower is selling #2 Diesel
                                (0.05% sulfur), then the net
                                price for #2 Diesel (0.05%
                                sulfur), less $.02/gal.

Coker Distillate Oil            Same as Raw Distillate Oil net
                                price.

JP-4                            Same net price used for Naphtha.

Heavy Fuel                      Same as Wyoming Sour Crude Oil
                                net price times 60%.

Cutter Stock                    Same price as Heavy Fuel.

Slurry                          Platt's Gulf Coast Resid, less
                                $6.00/barrel.

Vac Bottoms                     Same average net price used for
                                Asphalt.

HP Vac Bottoms                  Same average net price used for
                                Asphalt.

Unfinished Gasoline             Same price as Unleaded Regular
                                Gasoline, less $.025/gal.

As used in this schedule, "net price" means the reference price
less the specified adjustment amount.

The Agent reserves the right to adjust any of the above
methodologies for determining market value if any of the sources
of price information is no longer representative of market
prices.
July 1, 1995



Frontier Oil Corporation
1700 Lincoln, Suite 2100
Denver, Colorado 80203

Attention:  Mr. Jon D. Galvin
            Vice President and Chief
              Financial Officer

Re:         Fourth Amendment to Guaranty

Gentlemen:

     We refer to the Guaranty made by Frontier Oil Corporation
(the "Guarantor") as of August 18, 1992, as amended by a First
Amendment to Guaranty dated as of October 8, 1992, a letter of
waiver and amendment dated March 17, 1993, a Second Amendment to
Guaranty dated July 6, 1994 (said Guaranty, as so amended, herein
called the "Guaranty"), in favor of (1) Union Bank, Banque
Paribas and Den norske Bank AS (the "Banks") and (2) Union Bank,
as agent (the "Agent") for the Banks.  Unless otherwise defined
herein, terms defined in or pursuant to the Guaranty are used
herein as therein defined.

     The Guarantor has requested that Section 7.2(k) of the
Guaranty (concerning liquidity coverage) be amended as set forth
below, and the Banks are willing to do so.  Accordingly, the
parties hereby agree that, effective as of May 1, 1995, Section
7.2(k) of the Guaranty is amended in full to read as follows:

          "(k) Maintenance of Liquidity Coverage Ratio.  The
Guarantor will not permit the consolidated Liquidity Coverage
Ratio of it and its Subsidiaries as of the end of any calendar
month to be less than 1.08 to 1.0."

     On and after the effective date of this letter amendment,
each reference in the Guaranty to "this Guaranty," "hereunder,"
"Hereof," "herein" or words of like import referring to the
Guaranty, and each reference in the other Credit Documents to
"the FOC Guaranty," "thereunder," "thereof," "therein" or words
of like import referring to the Guaranty, shall mean and be a
reference to the Guaranty as amended by this letter amendment. 
The Guaranty, as amended by this letter amendment, is and shall
continue to be in full force and effect and is hereby ratified
and confirmed in all respects.

     This letter amendment may be executed in any number of
counterparts and by any combination of the parties hereto in
separate counterparts, each of which counterparts shall be an
original and all of which taken together shall constitute one and
the same letter amendment.

     If you agree to the terms and provisions hereof, please
evidence your agreement by executing and returning five
counterparts of this letter amendment to the Agent.  This letter
amendment shall become effective as described above when it has
been executed and delivered by all of the parties hereto and when
the Agent has received the following documents from the
Guarantor, in form and substance satisfactory to the Agent:  (1)
copies of the resolutions of the Board of Directors of the
Guarantor approving this letter amendment and any documents
delivered by the Guarantor in connection herewith, certified by
the Secretary or an Assistant Secretary of the Guarantor to be
correct and complete and in full force and effect as of the date
of execution, and as of the effective date, of this letter
amendment; and (2) a certificate of the Secretary or an Assistant
Secretary of the Guarantor as to the incumbency, and setting
forth a specimen signature, of each of the persons who has signed
this letter amendment or any document delivered by the Guarantor
in connection herewith.

Very truly yours,

UNION BANK, as Agent and as a Bank



By:  /s/ Richard P. DeGrey, Jr.
     --------------------------
     Richard P. DeGrey, Jr.
     Vice President


Agreed as of the date
first written above:


FRONTIER OIL CORPORATION



By:  /s/ Jon D. Galvin
     -----------------
     Jon D. Galvin
     Vice President and
       Chief Financial Officer



BANQUE PARIBAS


By: /s/ Mark M. Green
    -----------------
Name:  Mark M. Green
Title:  Vice President



By:  /s/ Barton D. Schouest
     ----------------------
Name:  Barton D. Schouest
Title:  Group Vice President



DEN NORSKE BANK AS



By:  /s/ Theodore S. Jadick, Jr.
     ---------------------------
Name:  Theodore S. Jadick, Jr.
Title:  Senior Vice President



By:  /s/ Fran Meyers
     ---------------
Name:  Fran Meyers
Title:  Vice President