SUBSIDIARY GUARANTY AGREEMENT

         THIS SUBSIDIARY GUARANTY AGREEMENT (this "Subsidiary Guaranty"),  dated
as of  October  15,  2003,  is made by San  Joaquin  Oil & Gas,  Ltd.,  a Nevada
corporation (the  "Guarantor") to the Lenders (as set forth in Exhibit A hereto)
under the  Debentures  (as  defined  herein)  (collectively  referred  to as the
"Lender")  and to Renn Capital  Group,  Inc.,  as the Agent for the Lenders (the
"Agent"). Capitalized terms used but not otherwise defined herein shall have the
meanings ascribed to them in the Loan Agreement (as hereinafter defined)

                              W I T N E S S E T H:

         WHEREAS, Gasco Energy, Inc., a Nevada corporation (the "Company"),  and
the Lender have entered into that certain Convertible Loan Agreement dated as of
October  15,  2003 (as from  time to time  amended,  supplemented  or  otherwise
modified, the "Loan Agreement"); and

         WHEREAS, the Guarantor is a wholly-owned  subsidiary of the Company and
will benefit from the  availability of credit to the Company under the terms and
conditions of the Loan Agreement and the Debentures.

         NOW,  THEREFORE,  to induce the Lender to execute  and deliver the Loan
Agreement  and  perform  their  obligations  thereunder,  and for other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto hereby agree as follows:

1. GUARANTY. The Guarantor hereby unconditionally,  absolutely,  continually and
irrevocably  guarantees to the Lender the payment and performance in full of the
Liabilities  (as defined below).  For all purposes of this Subsidiary  Guaranty,
"Liabilities" means:

     (a)  the Company's  prompt payment in full, when due or declared due and at
          all such times, of all Obligations and all other amounts,  heretofore,
          now or at any time or times hereafter owing,  arising, due or payable,
          whether  direct or  contingent,  joint,  several or independent of the
          Company  to  the  Lender,   including  without  limitation  principal,
          interest,  premium or fee (including,  but not limited to,  attorneys'
          fees and expenses); and

     (b)  the Company's prompt,  full and faithful  performance,  observance and
          discharge  of each and  every  agreement,  undertaking,  covenant  and
          provision to be performed, observed or discharged by the Company under
          any  instrument,  agreement or other  document with or in favor of the
          Lender.

         The  Guarantor's  obligations  to  the  Lender  under  this  Subsidiary
Guaranty   are   hereinafter   collectively   referred  to  as  the   "Guarantee
Obligations."  The Guarantor agrees that it is directly and primarily liable for
the Guarantee  Obligations  and that there are no  conditions  whatsoever to the
effectiveness  of this Subsidiary  Guaranty or to its obligations to perform the
Guarantee Obligations.

                                       1


2.  PAYMENT.  If the  Company  shall  default in payment or  performance  of any
Liabilities,  whether  principal,  interest,  premium,  fee (including,  but not
limited to,  attorneys' fees and expenses),  or otherwise,  when and as the same
shall become due,  whether  according to the terms of the  Debentures,  the Loan
Agreement  or the Loan  Documents by  acceleration,  or  otherwise,  or upon the
occurrence  of any other  Event of Default  (as  defined in the Loan  Agreement)
under the Loan  Agreement or the  Debentures  that has not been cured or waived,
then the  Guarantor,  upon  demand  thereof by the Lender or its  successors  or
assigns,  will, within three (3) business days of such demand,  fully pay to the
Lender an amount equal to all Guarantor's Obligations then due and owing.

3.  UNCONDITIONAL  OBLIGATIONS.  This  is a  guaranty  of  payment  and  not  of
collection.  The Guarantor's Obligations under this Subsidiary Guaranty shall be
absolute  and   unconditional   irrespective   of  the  validity,   legality  or
enforceability of the Debentures,  and shall not be affected by any action taken
under the Debentures or any other  agreement  between the Lender and the Company
or any other person, in the exercise of any right or power therein conferred, or
by any failure or omission to enforce  any right  conferred  thereby,  or by any
waiver of any covenant or condition therein provided,  or by any acceleration of
the maturity of any of the  Liabilities,  or any transfer or  disposition of any
assets of the Company or by any extension or renewal of the Debentures, in whole
or in part, or by any modification,  alteration,  amendment or addition of or to
the Debentures, or any other agreement between the Lender and the Company or any
other person, or by any other circumstance whatsoever (with or without notice to
or knowledge of the Guarantor) which may or might in any manner or to any extent
vary  the  risks of the  Guarantor,  or might  otherwise  constitute  a legal or
equitable discharge of a surety or guarantor; it being the purpose and intent of
the parties hereto that this Subsidiary Guaranty and the Guarantor's Obligations
hereunder shall be absolute and  unconditional  under any and all  circumstances
and  shall  not be  discharged  except  by  payment  as  herein  provided.  This
Subsidiary  Guaranty  shall  continue  in full  force and  effect and Lender may
continue  to  act  in  reliance  thereon   notwithstanding  the  termination  or
revocation  of  any  other  guaranty  of  Liability,   the  death,   disability,
incompetence or incapacity of the Guarantor, and shall be binding upon Guarantor
and Guarantor's  estate and the personal  representatives,  heirs and successors
and assigns of Guarantor, who shall, nevertheless, remain liable with respect to
Obligations and any renewals or extensions thereof or liabilities arising out of
same, and the Lender shall have all the rights herein provided for as if no such
event has occurred.

4.  CURRENCY AND FUNDS OF PAYMENT.  The  Guarantor  hereby  guarantees  that the
Guarantor's  Obligations will be paid in lawful currency of the United States of
America and in immediately available funds, regardless of any law, regulation or
decree  now or  hereafter  in  effect  that  might  in  any  manner  affect  the
Liabilities,  or the rights of the Lender  with  respect  thereto as against the
Company,  or cause or permit to be invoked any alteration in the time, amount or
manner of payment by the Company of any or all of the Company's Liabilities.

5. EVENTS OF DEFAULT. In the event that

                                       2


     (a)  the  Guarantor  shall  file  a  petition  to  take  advantage  of  any
          insolvency statute,

     (b)  the Guarantor  shall  commence or suffer to exist a proceeding for the
          appointment of a receiver,  trustee,  liquidator or conservator of all
          of or substantially all of its property;

     (c)  the Guarantor  shall file a petition or answer seeking  reorganization
          or arrangement or similar relief under the Federal  bankruptcy laws or
          any other applicable law or statute of the United States of America or
          any state or similar law of any other country;

     (d)  a court of competent  jurisdiction  shall enter an order,  judgment or
          decree  appointing  a  custodian,  receiver,  trustee,  liquidator  or
          conservator  of  the  Guarantor  of all  or  substantially  all of its
          properties,  or approve a petition filed against the Guarantor seeking
          reorganization  or  arrangement  or similar  relief  under the Federal
          bankruptcy  laws or any other  applicable law or statute of the United
          States of America or any state or similar law of any other country, or
          if,  under the  provisions  of any other law for the  relief or aid of
          debtors,  a court of competent  jurisdiction  shall assume  custody or
          control of the Guarantor of all or substantially all of its properties
          and such  order,  judgment,  decree,  approval or  assumption  remains
          unstayed or undismissed for a period of thirty (30) days;

     (e)  there is commenced  against the Guarantor  any  proceeding or petition
          seeking  reorganization,  arrangement  or  similar  relief  under  the
          Federal  bankruptcy laws or any other applicable law or statute of the
          United  States of America or any state,  which  proceeding or petition
          remains unstayed or undismissed for a period of thirty (30) days;

     (f)  the  Company or the  Guarantor  shall fail to  perform  any  agreement
          herein or contained in the Loan  Documents,  including but not limited
          to the Mortgages,  and such failure  remains uncured or unwaived for a
          period of thirty (30) days;

     (g)  a default  occurs in the punctual  payment of any sum payable upon any
          of the Guarantee Obligations or the Liabilities;

     (h)  entry of a  judgment  or  issuance  of a warrant of  attachment  or an
          injunction against, or against any of the property of the Guarantor;

     (i)  there shall occur an Event of Default under the  Debentures,  the Loan
          Agreement, or any Loan Document;

     (j)  any default shall occur in the payment of amounts due hereunder; or

     (k)  any other  default  shall occur  hereunder  which  remains  uncured or
          unwaived  for a period of thirty (30) days (each of the  foregoing  an
          "Event of  Default"  hereunder);  then at the  Lender's  election  and
          without  notice thereof or demand  therefor,  so long as such Event of
          Default  shall  be  continuing,   the  Guarantee   Obligations   shall
          immediately become due and payable.

                                       3


6. SUITS. The Guarantor from time to time shall pay to Lender,  within three (3)
business  days of  demand  by the  Lender  therefor,  at the  Lender's  place of
business set forth in the Debentures,  the Guarantee  Obligations as they become
or are declared  due,  and in the event such payment is not so made,  the Lender
may proceed to suit against the Guarantor. At the Lender's election, one or more
and  successive or concurrent  suits may be brought hereon by the Lender against
the Guarantor,  whether or not suit has been commenced against the Company,  and
whether  or not the  Lender  has taken or  failed  to take any  other  action to
collect all or any portion of the Liabilities.

7.  SET-OFF AND WAIVER.  The  Guarantor  waives any right to assert  against the
Lender as a defense, counterclaim, set-off or cross claim, any defense (legal or
equitable) or other claim which such  Guarantor may now or at any time hereafter
have  against  the Company or the Lender.  If at any time  hereafter  the Lender
employs  counsel for advice or other  representation  to enforce  the  Guarantee
Obligations that arise out of an Event of Default, then, in any of the foregoing
events, all of the attorneys' fees and disbursements  arising from such services
and all expenses,  costs and charges in any way or respect arising in connection
therewith or relating  thereto shall be paid by the Guarantor to the Lender,  on
demand.

8. WAIVER; SUBROGATION.

          (a) The Guarantor  hereby  waives  notice of the  following  events or
     occurrences:

               (i) the Lender's acceptance of this Subsidiary Guaranty;

               (ii) the Lender  heretofore,  now or from time to time  hereafter
          loaning monies or giving or extending  credit to or for the benefit of
          the Company,  whether  pursuant to the  Debentures or any  amendments,
          modifications,  or supplements  thereto, or replacements or extensions
          thereof;

               (iii) the Lender or the  Company  heretofore,  now or at any time
          hereafter,  obtaining, amending,  substituting for, releasing, waiving
          or modifying the Debentures, the Loan Agreement or the Loan Documents;

               (iv)  presentment,   demand,  notices  of  default,  non-payment,
          partial  payment,  notice of dishonor,  suit,  protest or taking other
          action by the Lender;

               (v) the Lender heretofore,  now or at any time hereafter granting
          to the Company (or any other party  liable to the Lender on account of
          the  Liabilities)  any  indulgence or extensions of time of payment of
          the Liabilities;

                                       4


               (vi)  any  agreement  among  any of  holders  of  the  Debentures
          relating to this Subsidiary Guarantee or any other matter; and

               (vi)  the  Lender  heretofore,  now  or  at  any  time  hereafter
          accepting from the Company or any other person, any partial payment or
          payments on account of the Liabilities or any collateral  securing the
          payment thereof or the Lender settling,  subordinating,  compromising,
          discharging or releasing the same.

     The  Guarantor  agrees that the Lender may  heretofore,  now or at any time
     hereafter do any or all of the  foregoing  in such manner,  upon such terms
     and at such times as the Lender, in its sole and absolute discretion, deems
     advisable, without in any way or respect impairing,  affecting, reducing or
     releasing such Guarantor from the Guarantee Obligations,  and the Guarantor
     hereby consents to each and all of the foregoing events or occurrences.

          (b) The Guarantor  hereby agrees that payment or  performance  by such
     Guarantor of the Guarantee  Obligations under this Subsidiary  Guaranty may
     be  enforced  by the Lender  upon  demand by the  Lender to such  Guarantor
     without the Lender being  required,  the  Guarantor  expressly  waiving any
     right it may have to require the Lender, to prosecute collection or seek to
     enforce or resort to any remedies  against the Company,  IT BEING EXPRESSLY
     UNDERSTOOD,  ACKNOWLEDGED  AND AGREED TO BY THE GUARANTOR THAT DEMAND UNDER
     THIS  SUBSIDIARY  GUARANTY  MAY BE MADE BY THE LENDER,  AND THE  PROVISIONS
     HEREOF ENFORCED BY THE LENDER,  EFFECTIVE AS OF THE FIRST DATE ANY EVENT OF
     DEFAULT  OCCURS  AND IS  CONTINUING  UNDER THE  DEBENTURES.  The  Guarantee
     Obligations shall in no way be impaired,  affected, reduced, or released by
     reason of the  Lender's  failure or delay to do, take or enforce any of the
     acts,  actions or things described in this Subsidiary  Guaranty  including,
     without limiting the generality of the foregoing,  those acts,  actions and
     things described in this Section 8.

          (c) The  Guarantor  further  agrees  with  respect to this  Subsidiary
     Guaranty  that  such  Guarantor   shall  have  no  right  of   subrogation,
     reimbursement  or indemnity until such time as all of the Liabilities  have
     been fully, finally and indefeasibly paid in full.

9. EFFECTIVENESS; ENFORCEABILITY. This Subsidiary Guaranty shall be effective as
of the date  hereof,  and shall  continue  in full  force and  effect  until the
Liabilities  have  been  fully,  finally  and  indefeasibly  paid in full.  This
Subsidiary  Guaranty  shall be  binding  upon and  inure to the  benefit  of the
Guarantor  and  the  Lender  and  their   respective   successors  and  assigns.
Notwithstanding  the  foregoing,  Guarantor  may not,  without the prior written
consent  of the  Lender,  assign  any  rights,  powers,  duties  or  obligations
hereunder.  Any claim or claims that the Lender may at any time  hereafter  have
against the  Guarantor  under this  Subsidiary  Guaranty  may be asserted by the
Lender by written  notice  directed to the  Guarantor  at the address  specified
herein.

                                       5


10. AGENT FOR LENDER.  Guarantor  recognizes and agrees that pursuant to Section
11.03 of the Loan Agreement,  Lender has designated and appointed Agent as agent
for Lender under the Loan Agreement and under this Subsidiary Guaranty with full
power to act for and on behalf of Lender,  and each of them, and to exercise all
of the rights and privileges of Lender,  and each of them, under this Subsidiary
Guaranty  and under each of the Loan  Agreements.  Guarantor  has  reviewed  the
provisions of the Loan Agreement and each of the Loan Documents,  including, but
not limited to the  provisions of Section 11.03 of the Loan Agreement and agrees
that any notice from or agreement of Agent taken in the capacity as the agent of
Lender,  shall be binding upon and constitute  the act of the Lender,  or any of
them and that in acting as agent of  Lender,  Agent  has not  assumed  nor shall
there be implied any obligation  toward or  relationship of agency or trust with
Guarantor or the Company or any of their  respective  affiliates.  In exercising
any rights or engaging in any transaction  contemplated  hereunder,  Agent shall
not be obligated to provide  Guarantor  with evidence of its authority to act as
the agent of Lender,  or any of them,  unless Lender,  acting on its own behalf,
shall have previously provided Guarantor with evidence that acting in accordance
with its rights,  Lender,  or any of them,  have revoked Agent's agency capacity
with regard to its affairs.

11.  REPRESENTATIONS  AND WARRANTIES.  The Guarantor  hereby makes the following
representations and warranties to the Lender:

     (a)  the Guarantor is duly authorized to execute,  deliver and perform this
          Subsidiary Guaranty;

     (b)  this  Subsidiary  Guaranty is legal,  valid,  binding and  enforceable
          against  such  Guarantor  in  accordance  with  its  terms  except  as
          enforceability    may   be   limited   by   bankruptcy,    insolvency,
          reorganization,  moratorium or similar laws affecting the  enforcement
          of creditors' rights generally and by general equitable principles;

     (c)  such   Guarantor's   execution,   delivery  and  performance  of  this
          Subsidiary  Guaranty  does not violate or  constitute  a breach of any
          agreement to which such Guarantor is a party, or any applicable laws;

     (d)  Guarantor makes each of the representations  and warranties  contained
          in Article III of the Loan Agreement as if set forth in their entirety
          herein with respect and reference to the Guarantor and this Subsidiary
          Guaranty; and

     (e)  no representation or warranty made by the Guarantor in this Subsidiary
          Guaranty,  the Loan Agreement or any  Transaction  Document nor in any
          document,  written  information,   financial  statement,  certificate,
          schedule or exhibit  prepared  and  furnished  or to be  prepared  and
          furnished   by   Guarantor  in   connection   with  the   transactions
          contemplated hereby,  contains or will contain any untrue statement of
          a  material  fact,  or omits or will  omit to  state a  material  fact
          necessary to make the statements or facts contained  herein or therein
          not  misleading  in light of the  circumstances  under which they were
          furnished.

                                       6


12. NEGATIVE COVENANTS. The Guarantor agrees that until the Debentures, together
with interest and all other  Obligations  of the Company or the Guarantor to the
Lender (whether under the Loan Agreement,  the Loan Documents, or otherwise) are
paid in full, the Guarantor shall not,  without the prior written consent of the
Lender:

          (a) Create,  incur,  assume or suffer to exist any lien upon or defect
     in title to or restriction upon the use of any of the property or assets of
     the  Guarantor  of any  character,  whether  owned  at the date  hereof  or
     hereafter  acquired,  or hold or  acquire  any  property  or  assets of any
     character under conditional  sales,  finance lease or other title retention
     agreements, except for Permitted Liens and liens in favor of the Lender.

          (b)  Create,  incur,  assume  or  suffer  to  exist,  contingently  or
     otherwise,   any  indebtedness,   except  for  Permitted  Indebtedness  and
     indebtedness to the Lender.

          (c) Make or have any  Investments not permitted by Section 6.03 of the
     Loan Agreement.

          (d) Make any prepayment of indebtedness that is prohibited by the Loan
     Agreement.

          (e) Enter into any agreement  which prohibits or limits the ability of
     the Guarantor to create,  incur,  assume or suffer to exist any lien,  upon
     any of its  property,  assets or  revenues,  whether now owned or hereafter
     acquired.

          (f) Change the  address of its  principal  place of  business  without
     giving 30 days' prior written notice to the Lender.

13. AFFIRMATIVE  COVENANTS.  The Guarantor  covenants and agrees that, until the
Debentures  together with interest and all other  Liabilities of the Company and
the  Obligations  of the Guarantor to the Lender under the Loan  Agreement,  the
Debentures and the Loan Documents are otherwise paid in full:

          (a)  Comply  with  all  statutes  and   governmental   regulations  if
     noncompliance  therewith  would  have  a  Material  Adverse  Effect  on the
     Guarantor and pay all taxes, assessments,  governmental charges, claims for
     labor,  supplies,  rent and any other  obligation  which, if unpaid,  might
     become a lien against any of its  properties,  except any of the  foregoing
     being  contested  in  good  faith  by  appropriate  proceedings  diligently
     conducted and against which adequate reserves have been established;

          (b) It will  allow  any  representative  of the  Lender  to visit  and
     inspect the books of account and other records and files of the  Guarantor,
     to make copies thereof and to discuss the affairs,  business,  finances and
     accounts of the Company and the Guarantor  with its  employees,  all during
     normal business hours and as often as the Lender may reasonably request;

                                       7


          (c) It will duly  comply  with all the terms and  covenants  contained
     herein and in each of the  instruments and documents given to the Lender in
     connection  with  or  pursuant  to  this  Subsidiary  Guaranty,   the  Loan
     Agreement,  the Debentures and the other Loan  Documents,  all at the times
     and places and in the manner set forth herein or therein;

          (d) It will  keep  all  properties  of the  Guarantor,  whether  real,
     personal or mixed,  free and clear of all liens,  other than the  Permitted
     Liens and liens created by the Loan Documents.;

          (e)

               (i) It  will  keep  all of its  insurable  properties  adequately
          insured at all times with responsible  insurance carriers against loss
          or damage by fire and other hazards as are customarily insured against
          by similar businesses owning such properties similarly situated and

               (ii) maintain  general  public  liability  insurance at all times
          with responsible  insurance  carriers against  liability on account of
          damage to persons and property such  insurance  policies to be in form
          reasonably satisfactory to the Lender;

          (f) It will keep or cause to be kept, true books of record and account
     in which full, true an correct entries shall be made of all of its dealings
     and transactions in accordance with customary business practices; and

          (f) Upon the Guarantor  obtaining knowledge of any litigation or other
     proceedings being instituted  against the Guarantor,  any of the Company or
     any subsidiary of the Company, or any attachment,  levy, execution or other
     process being instituted against any assets of the Guarantor or the Company
     or  any  subsidiary,  in  an  aggregate  amount  in  respect  of  all  such
     proceedings  and processes  greater than $50,000 not  otherwise  covered by
     insurance,  it will promptly  deliver to the Lender  written notice thereof
     stating  the  nature and status of such  litigation,  dispute,  proceeding,
     levy, execution or other process.

14. EXPENSES.  The Guarantor agrees to be liable for the payment of all fees and
expenses,  including  attorney's  fees and  expenses,  incurred by the Lender in
connection with the enforcement of this Subsidiary Guaranty.

15.  REINSTATEMENT.  The Guarantor  agrees that this  Subsidiary  Guaranty shall
continue  to be  effective  or be  reinstated,  as the case may be,  at any time
payment received by the Lender under the Debentures or this Subsidiary  Guaranty
is  rescinded  or must be restored for any reason.  The  execution  and delivery
hereafter  to Lender by  Guarantor  of a new  instrument  of guaranty  shall not
terminate,  supersede  or cancel  this  instrument,  unless  expressly  provided
therein, and all rights and remedies of Lender hereunder or under any instrument
of guaranty  hereafter  executed and  delivered to Lender by Guarantor  shall be
cumulative and may be exercised singly or concurrently.

                                       8


16.  COUNTERPARTS.  This  Subsidiary  Guaranty  may be executed in any number of
counterparts,  each of which  shall be deemed to be an  original  as against any
party whose signature appears thereon, and all of which shall constitute one and
the same instrument.

17. RELIANCE. The Guarantor represents and warrants to Lender that:

     (a)  such  Guarantor  has adequate  means to obtain from the Company,  on a
          continuing  basis,  information  concerning  the  Company's  financial
          condition  and affairs and has full and  complete  access to Company's
          books and records;

     (b)  such  Guarantor  is not  relying  on the  Lender,  its agents or other
          representatives, to provide such information, now or in the future;

     (c)  such  Guarantor  is  executing  this  Subsidiary  Guaranty  freely and
          deliberately,  and  understands  the  obligations  and financial  risk
          undertaken by providing this Subsidiary Guaranty;

     (d)  such Guarantor has relied solely on the  Guarantor's  own  independent
          investigation,  appraisal  and  analysis  of the  Company's  financial
          condition and affairs in deciding to provide this Subsidiary  Guaranty
          and is fully aware of the same; and

     (e)  such Guarantor has not depended or relied on the Lender, its agents or
          other  representatives,  for any information whatsoever concerning the
          Company's financial condition and affairs or other matters material to
          such Guarantor's  decision to provide this Subsidiary  Guaranty or for
          any  counseling,  guidance,  or special  consideration  or any promise
          therefor with respect to such decision.  The Guarantor agrees that the
          Lender has no duty or responsibility whatsoever, now or in the future,
          to provide to the Guarantor any  information  concerning the Company's
          financial  condition  and affairs,  other than as  expressly  provided
          herein, and that, if such Guarantor receives any such information from
          the Lender, its agents or other  representatives,  such Guarantor will
          independently  verify the information and will not rely on the Lender,
          its agents or other representatives, with respect to such information.

18. COMPLETE  AGREEMENT.  This Subsidiary  Guaranty and the other Loan Documents
embody the whole  agreement of the parties with respect to the subject matter in
the Loan  Documents  and may not be  modified  unless in  writing  and signed by
Lender and no course of dealing between  Guarantor and Lender shall be effective
to  change  or  modify  or to  discharge  in  whole or in part  this  Subsidiary
Guaranty.  No Waiver of any right or power of Lender or  consent  by it shall be
valid unless in writing signed by an authorized officer.

19.  TERMINATION.  This Subsidiary Guaranty and all obligations of the Guarantor
hereunder shall terminate  without  delivery of any instrument or performance of
any act by any party on the date when all of the  Liabilities  have been  fully,
finally and indefeasibly paid in full.

                                       9


20. GOVERNING LAW. THIS SUBSIDIARY  GUARANTY SHALL BE GOVERNED BY, AND CONSTRUED
IN ACCORDANCE  WITH,  THE LAWS OF THE STATE OF COLORADO  APPLICABLE TO CONTRACTS
EXECUTED, AND TO BE FULLY PERFORMED, IN SUCH STATE.

21. NOTICES. Any notice hereunder shall be in writing, and shall be delivered by
overnight courier service or by certified mail, postage prepaid,  return receipt
requested, addressed as follows: If to the Guarantor:
         Pannonian Energy, Inc.14 Inverness Drive
         EastBuilding H, Suite 236
         Englewood, CO 80112
         Attn:    Mark Erickson
         Telephone:        (303) 483-0044
         Telecopier:       (303) 483-0011




with a copy simultaneously transmitted by like means to:
         Vinson & Elkins L.L.P.
         2300First City Tower
         1001 Fannin
         Houston, Texas  77002
         Attn:    Michael Finch
         Telephone:        (713)-758 -2158
         Telecopier:       (713) 615-5282


                  If to the Lender,  to all of the addresses set forth under the
Lenders' names on the execution page to the Loan Agreement,  with a copy,  which
shall not constitute notice, simultaneously transmitted by like means to:
Jackson Walker L.L.P.
901 Main Street
Ste 6000
Dallas, Texas 75202
U.S.A. Facsimile: (214) 953-5822 Attn: Jeffrey M. Sone, Esq.



Notices sent by overnight  courier service shall be deemed delivered on the next
business  day, and notices  sent by  certified  mail,  postage  prepaid,  return
receipt requested, shall be deemed delivered two business days after the date of
mailing thereof.

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         IN WITNESS  WHEREOF,  the parties have duly  executed  this  Subsidiary
Guaranty on the day and year first written above.

GUARANTOR:

SAN JOAQUIN OIL & GAS, LTD.

By:________________________________
Name:
Title:

LENDER:

RENAISSANCE CAPITAL GROWTH & INCOME FUND III, INC.

By:__________________________________________

Name:
Title:

BFSUS SPECIAL OPPORTUNITIES TRUST PLC

By:__________________________________________
Name:
Title:

RENAISSANCE US GROWTH & INCOME TRUST PLC

By: __________________________________________

Name:
Title:

AGENT:

RENN CAPITAL GROUP, INC.

By:__________________________________________

Name:
Title:





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